Hello,
I would like to share with you how I taught my veiled chams to love handling and ask for my attention, I am a positive reinforcment dog and cat trainer, I know that chams are way different but I read in one of my Cham books that chameleons will and can retain information..

when I was doing my research before buying my first ever female chameleon I saw and read alot on how aggressive and stressed they can be during handling so I thought I'd teach them in the lowest stress way possible! How did I do it? FOOD ASSOCIATION of coarse! How I started was baby steps,
first I hand fed, then I simply held my hand in front of my girl and the food cup a little closer toward my elbow and let her make the CHOICE to step onto my hand, when she did she also ate her food on my hand, when she was comfortable stepping onto me and after her breakfast she was allowed to free range in her own jungle gym of vines and sticks above her cage

this made her associate me with not only food but also more freedom!! And this was all done by her choice in the least stressfull way possible, my goal was not to train but to avoid aggression and stress completely while handling, so far I'm the only one I know of who has tried it.
Now thanks to my patients and somewhat easy work she really enjoys coming out and being handled and since it's by her own choice it keeps the stress of it all way down if any!and imagine the advantage you will have if you ever need to handle for medical reasons!
I recently got a 3 month old male veiled and I have been using the same process with him for the past month iv had him and I'm getting the same results!!!!
here is my female walking onto my hand with no food lure she now eats in her cage and walks onto me for free range time
http://m1281.photobucket.com/albumview/albums/takani1/1362382031_zpse40788aa.jpg.html
i hope ull give it a try
and feel free to let me kno how it goes,
and I don't know if you will have the same results but it worked for me it's worth a try