I have asked this question all over, and finally answered it myself as I took this route yesterday. I wanted to be detailed so other travellers could use this information. Reminder -- after April 16, the bus section is invalid as TRAX will be running by then.
Getting from airport to Provo via Frontrunner
Starting April 16, 2013 TRAX will be running from the airport to Central Station. Until then you need to take the UTA bus. Fare is $2.35, have exact change as they do not give change. They have a credit card machine it may only take electronic swipe. Pay pass?
From Salt Lake Airport, exit either terminal on the upper floor skywalk towards the garages. Between the two terminals inside the parking structure is a UTA bus stop. Take the bus to the Salt Lake Central Station (this is where most people will get off the bus). It's about 15 minutes or so. It takes an odd route through downtown, but never fear, you will be there soon. You will get a transfer ticket, when you get on the bus, so keep that, it will lower your Frontrunner fee (to American Fork cost me an additional $2.20.
Right as you get off you will be in front of the tracks. Do not go indoors. There is a ticket machine that takes credit cards. Follow instructions.. Remember to select that you have a transfer ticket. You are at the Southbound track, crossover track if you need to go Northbound. There is a sign that tells you how long before the next train departs.
Note: there is no where to stay that is warm, and you could be there from 5 minutes to an hour depending on time of day, so plan ahead. Frontrunner does NOT run on Sunday ... Only TRAX and bus.