Hi,
I applied inland 2 years ago and I went to the Mexican consulate in Vancouver, they can give you the letter you need to get the Constancia de datos registrales. You will need to send this letter with a Carta Poder to someone (family,friend,etc) to go to the PGR and do everything for you in Mexico city. You will get the Constancia in 2 weeks but you can do this only If you apply inland.
I'm applying inland, and yes i have my parents living in mexico. They live in another city (2 days driving or 3 hours flight). They will have to go twice (about $1000), besides theyhave lived all their life in an small town, so Mexico City can be a little bit dangerous to for them.
I wish somebody has done it before with this company. Just to make sure about they are for real.