From Smoth, with editting by me...
http://www.smoth.net/home/spring/skyboxsources.7z
Render each pre-set view - 1,2,3,4 and so on - into a directory.
This
(altored1) is an example with pre-built bat and .lst file.
You will need Nvidia's texture tools, I link them and detail the usage here:
http://springrts.com/wiki/Skyboxcreation
The big trick to skyboxes is getting the camera and viewport settings right, these files have that so feel free to use them as a base for your skyboxes.
I would put up images of how to find what where, but that can be found on google pretty easily, the big thing to remember...
The only setting you need worry about is Link Sun To View deactivate it. That will be found in skylab, again, if lost, google
I hope this helps you guys.