LabVIEW's built-in XNode editing tools are enabled using a license file, rather than a simple INI toggle. Presumably they do this for stronger discouragement from unofficial use, as hacking one's way past that feels a lot more "shady" than just adding a line to a config file.
But what about the Linux and Mac versions? They don't have a license manager, so how is XNode development enabled there? One might guess that those features simply aren't compiled into the released builds of those versions, but there is actually precedent to suggest otherwise. VI Scripting used to be similarly restricted using a license, but then they made it public. At the time, LabVIEW didn't have a toggle in the Options for it. But they didn't need to release a patch to add one. Instead, they simply published their formerly-internal license file, and set their activation server to accept requests to activate it. And yet, Linux/Mac users weren't out of luck: it turned out that for them, it actually was just a configuration key.
The VI Scripting license had the internal name "LabVIEW_Scripting(_PKG)". The Linux/Mac configuration key was "Scripting_LabVIEWInternalTag".
At 17:48 in this video, several XNode-related configuration keys are shown, likely found in strings in the EXE or resource files. One of them is called "XNodeDevelopment_LabVIEWInternalTag". Guess what the internal name of the XNode Development license is.
I don't have the Linux/Mac version to test with, but I know a pattern when I see one. The following command was given in the readme for the VI Scripting package for Linux:
echo -e "labview.Scripting_LabVIEWInternalTag:\tTrue" >> ~/.labviewrc Here are the Mac instructions:

If you have either of those versions, it's probably worth a try: follow those instructions, but replace "Scripting" with "XNodeDevelopment", and see if you can open an XNode in the IDE, or create one from File->New. (Also, in the case of Mac, replace 8.6 with your actual LabVIEW version if necessary.)
(Here's where I got my information about enabling scripting: https://forums.ni.com/t5/LabVIEW-APIs-Documents/LabVIEW-Scripting/ta-p/3535340?profile.language=en)

View File XNode Editor
8 Years ago the first version of the XNode Manager was posted to the code repository in an attempt to allow the editing of XNodes.  Being a fan of XNodes, but knowing that the XNode Manager is pretty limiting because of its age, I set out to make a new version with similar functionality.
The XNode Manager had a blank XNode, and blank Abilities that it just made copies of.  This is fine but then the abilities and XNode are quite old.  There were many new Abilities added since version 8.2 and you can't add them using the XNode Manager.  My XNode Editor reads your LabVIEW resource and populates the list of abilities to create from the ones that are possible to create.  Then VI server is used to create the XNode, State control, and Abilities.  This sets up the connector pane like it should and should work with all future versions of LabVIEW, until NI changes something that breaks it.  It also reads in the XNode Ability descriptions to help understand how to use the new ability VIs.
In addition to being able to create and edit XNodes, you also can edit the XNode icon, and description, along with adding any new abilities.
Be aware this uses several private functions, and several undocumented features that could be potentially bad.  I did a decent test to make sure memory leaks weren't a problem and I made several XNodes and Abilities and it seems stable.  But at the end of the day if it blows up and crashes, don't be surprised, you've been warned.  The original thread with discussion and progress on this tool was started here.

Submitter hooovahh Submitted 03/15/2017 Category XNodes LabVIEW Version  

After working on the set cluster element by name xnode, it made me realize i could use the same concept to convert a variant array to a cluster. The technique is actually pretty simple, the xnode generates a case structure for each element in a cluster in cluster order, wherein a bundle by name is used to set the value and an unbundle by name is used to get the type, a variant to data is used to convert the data. This has some benefits over some methods, you are not limited to 255 elements, although that is not usually the case some of us are paranoid that clusterosaurus giganticous will be larger than expected. It also has a draw back  that is that when converting from a variant array all the elements must have unique, non-blank names, and this is usually the case. 

I think this technique (though very brute-force) might be useful for some other things let me know what you guys think.

VariantArrayToCluster.zip

This Xnode allows setting a cluster element by label string without using references. I pulled a great deal of inspiration from Hooovahhs Variant Array to cluster xnode, which i suppose this could be used for, another benefit is its not limited to 255 elements. Its mostly experimental because I haven't used it much. 
 
SetClusterElement.zip

SetClusterElementLV2013.zip

I've been working a lot lately with by-reference architectures that still cooperate completely with LabVIEW's implementation of OOP and polymorphism. I've also recently taken an interest in trying to speed up development with secondary providers (similar to GOOP) to enable automatic creation of accessor VIs hidden behind the DVR, automatic creation of the private data type and constructor/destructor, etc. within the project window. I'm generally not a fan of the extra stuff that goop adds in to classes, I'd prefer to keep the source code looking as close to a normal class as possible.
That said, I've started on my first ever XNode and it's a cross between an unbundle by name node and the -> operator in C. It functions just like a normal UBN, however it was also pull items out of DVRs. Having to plop down a UBN to pull out the reference from the class, an in place node to dereference, and then another UBN to pull the data out gets tiresome after about the 100th property VI gets written.
So far I've gotten the node drawing completed (except for data type coloring of the labels), the type inferencing from the input wire, and the popup menu for selecting an item. Next up will be the menu selection code so that the names will finally show up in the terminals! Then I get the daunting task of scripting up the GenerateCode ability >_>
Anyone interested in something like this? Following this will be a match to the Bundle by Name node that serves the same purpose except to write the items.