Sorry to revive such an old thread, but this is one of the top results when googling for libsvm and LabVIEW. I've implemented a new interface to libsvm using call library function nodes instead of CINs. A parameter grid-search as in the original post isn't included, but should be fairly simple to build on top of the new interface. Note that the old interface passed data through text-files, while this new interface passes the data directly.
Feel free to try it out and report bugs. I'll continue to add features once I have some time on my hands. I'll probably submit it as an official interface, once I feel that it's stable enough and I've settled on the API.
The library is available at http://github.com/oysstu/LabVIEW-libsvm. Just download the provided VIPM package under releases.