I have it installed with ubuntu as host OS. It is not "supported" but seems to be fine. My team has not received the kit yet, but will see how it goes then.
Before I installed windriver workbench, I looked into building a GNU toolchain. Unfortunately I was not able to get gcc to completely build.
For those that want to continue on that route, you will need to download headers for vxworks. National instrument provides this for vxworks 6.1 and 6.3 (no idea what is on the controller we get from first).
http://zone.ni.com/devzone/cda/tut/p/id/5694
You can build binutils with the target powerpc-wrs-vxworks just fine. Trying to build gcc I had major issues relating to the headers.
Another alternative would be to use the compiler provided in workbench and create some makefiles. Not my preferred route, but it should work okay.