Hi Gamma, go to
http://www.faa.gov/licenses_certific..._verification/
Get this paperwork going as it takes at least 90 days to process.
This will convert you to a FAA private certificate, to convert your IFR you need to do a 50 question test. Get it sent to a local FSDO (long Beach is good if in LA)
Then find a school with commercial training, You will need to do the written and Flight test.
Away you go.
Cheers, WTA...