Two months ago I went into the Zacatecas INM office and asked about the rules for changing from Temporal to Permanente. They gave me 4 xeroxed pages of step by step.
When I went to work through it, I noticed that www.inm.gob.mx had changed quite a bit. The complete list of requirements doesn't seem to appear as you work through the process online. I suggest you stop in at an INM office and get the list of requirements from them, such as 3 photos (2 front, 1 profile), a letter stating you want to go from temporary to permanent based on having completed 4 years as temporal, you still have US income sufficient to support yourself, 3 months bank statements showing you still have the level of income you reported last year... There are others, I'm, that aren't listed on the website. Make it easy on yourself and ask before you appear with a wad of papers in your hand. One good thing is that if you are changing after 4 years as Temporal, the strict income requirements don't apply. My income is about 10% less than the published requirement.
At any rate, you go to www.inm.gob.mx and along the righthand side you'll find "Tramites Migratorios." Click it.
Then "Estoy en Mexico." Then "Cambio de Condicion." And then "De Residente Temporal a Residente Permanente." It is all in in Spanish but pretty much self explanatory.
I prepared my paperwork on Fri. Aug. 16 and showed up at INM at 9:15 AM on Monday. I was the only one in the office so I got attended to rightaway. It took maybe 15 minutes for the young lady to make sure everything was in order. Then she told me, "the 'Licenciado' has to sign off on everything before I can take your fingerprints. I'll print "Hojas de Ayuda" for the two payments you have to make at the bank, one for $3815MXN for the Residente Permanente and one for $1000MXN for Revision de Documentos." The bank was a 3 block walk. I actually waited in line for 20 minutes longer than I needed to. About 60 people were lined up for 1 transaction only. After the line moved a bit, I noticed an empty line for multiple transactions. 2 payments are multiple. I got receipts and was back at INM 45min. after I left.
By now, there were about a dozen other applicants waiting. The receptionist took my receipts and asked me to have a seat. 5 min later, the same young lady who helped me earlier called me up, took my fingerprints, had me sign a few forms and said that was all. I told her I had appointments in the US on the 29th and 30th and wished to apply for "Permiso de Salir y Regresar" and I had the application ready. She said that there was a good chance the Residente Permanente would be back by today, Mon Aug. 26, and anyway the Permiso is issued the same day so I could save myself $320MXN if I waited.
This morning I was having breakfast at Vips when my cel rang at 9:15 AM and it was INM saying my Residente Permanente was ready to pickup. It took me 15 min. to get over there and another 5 min. to verify that the data on the card was correct and sign a receipt for the card.
All in all a pretty painless process.