You are getting incredibly poor and really seriously bad advise by the above...
Sooo.. lets start from the top and get you in the right direction. If the fish has been feeding on only feeders for a long time, you have a challenge on your hands but it is not at all impossible to get the fish to a more varied and healthy diet.
There have been several posts about training gar to accept other foods. First please go through some of these threads and take each technique into account. All are valid and will work to varied degrees. What you need to understand and commit to is a process that will work for you and your situation.
This process will take patience and persistence on your part.
Keep with it, commit to it and do not give up until you have succeeded.
NEVER once have I ever not got a gar onto a varied diet of prepared and fresh foods. This is not at all difficult it just takes your commitment to doing so to make this work and succeed.
I suggest you try using the method known as drop training...
Drop training is where change the fishes feeding behavior to accept prepared foods. This technique is roughly explained by Oddball in Post #5 of this thread
http://www.monsterfishkeepers.com/forums/showthread.php?t=154716
In addition to pellets (of varied type) also try Shrimp and thawed frozen white flesh fish (I.E. tilapia, catfish, etc.) It may actually be better to start with the shrimp and fish before moving to pellets in your case as the smellier the food the better with stubborn cases.
Once a gar is trained in such a way as to let them ID foods that are not moving, you can substitute from this point a huge variety of foods items. Some they will relish and some not so much but they will take them...First things first though..
A fish on a varied diet of multiple foods will be much better off than one fed on only a singular feed item.
I hope this is a good start to get you in the
correct direction rather than the very poor and misleading info you have unfortunately been given thus far.