Try a small piece of tilapia fillet cut thin in the general shape of a feeder fish. Use a wooden skewer (May want to dull the point for your Gars comfort!), and stick the meat chunk like you would fish live lining. In otherwords you hook live line fish behing the dorsal so that they have good swim action, place the skewer into the meat chunk so that it somewhat resembles a feeder fish.
Be paitient and always use slow smooth movements. No quick jerky spook your gar junk!
A light "bonk" will occassionall get a perticularly stuborn gar to "strike" the pesky "meat chunk". I found, that once you get the gar to take the meat off the stick, either to eat or beat up, you have the problem licked, and your gars will be stick trained for life from that point on.
On a side note, since your gar came from a LFS, it is NOT a spotted gar as they are very often listed as. What you own is a Florida Gar! The Gar experts in the Ancient fish forum will all tell you the same thing. Without EXACT location of the collection point, all LFS spotted gars are truely Florida gars!