Look on the Palmetto 800 database page here: Palmetto 800 Trunking System, Various, Multi-State - Scanner Frequencies
Look not quite half way down the page for the Medical Helicopters talkgroup group. You'll hear them "toned out" on 38352 and communicating with FlightComm and the other Upstate MedTrans helicopters on 38368. Both of these are digital talkgroups, requiring a digital trunktracking scanner to monitor.
I have found that these talkgroups are limited to only a few towers in the upstate. You'll hear 38368 on several towers, including Greenville Simulcast (#35), Spartanburg Simulcast (#19), Anderson (#42) and some others. 38352 is certainly carried on Greenville Simulcast but not many others, so you'll need to monitor site #35 to hear all activity from GMH MedTrans.
Also see this wiki article: SC Medical Helicopters - The RadioReference Wiki