The requirement for the 30 months of experience to have been full time has always been the case. However, in general, the FAA has long taken the word of a certificated mechanic, employer, or other authoritative source in vouching for the experience. I have also seen the Administator demand proof of full time employment, and rightfully so.
Having obtained a statement for the FAA, short coruses are available through Bakers or Kings or other such places that enable you to wrap up your efforts and come away with the certificate in pocket.
When I did my certificate, I had about six years cumulative experience, which I documented by aircraft registration and work done on each aircraft, as well as about half a dozen letters from former employers attesting to the full time work done. After obtaining the authoirzation to test, I studied on my own for a year before going to a community college designated examiner. There I took an eight hour practical exam, and passed. Your mileage, of course, may vary.