Hi, Mynock! You can programmatically set Windows System Time as explained here:
http://digital.ni.com/public.nsf/3efedde43...54?OpenDocument
But, as you said, if you don't have Administrator or Power User privileges, you can't change system date or system time. You can run your program under a new created Power User account or, if you prefer run your program under a simple User account, you must change the "Change System Time" item in "User Right Assignment" in Windows "Local Security Settings" Console. Here the way to reach it:
Control Panel -> Administrative Tools -> Local Security Policy -> Local Policies -> User Rights Assignment.
Here you can find "Change the System Time" item. You have to add "Users" group to Security Setting List and reboot your machine. Now a simple User account can change system date and system time. I hope it will be useful for you.
Greetings