Well I have some experience with this, I had to force feed using that method on 3 leos at the same time for about a week... I don't know much about AFT, but they don't seem to be too much different from leos....
First here is a good recipe... from goldengategeckos
1 small can Hill's A/D pet food (available at most vets)
1/4 cup Ensure (not chocolate)
1/4 cup pedialite
1 jar baby food squash or 1/4 cup plain canned pumpkin
1/2 tsp. each calcium powder and herp vitamins
2 crushed tablets or 2 opened capsules of milk thistle (found at most places that have vitamin and herb supplements - it is a liver purifier) un-needed unless have prolonged malnurishment
* a handfull of mealworms puree'd with this mixture if you can deal with that!
- Pour slurry in ice cube trays and freeze, thawing out only what you will use in a few days.
Put it in a syringe and drip slowly on nose. Some will drink out of it making it easier as well. And rarely they might bite down on it, which is the quickest