I didn't make it!
On instant action I want to change the ships a race starts with, how can I do this?
Change the race's .odf file. (e.g. fed.odf, etc.).
Everytime I try that I get a ctd while loading a skirmish but, it obviously is possible...just not for me lolwut?
Well, download the Cerberus Class: That one is an example of a successful change (the altered fed.odf file is included, scroll to the bottom to see an example.) Look for "FCerb.odf". Copy that format.