I have an argentine b&w this is the advice I was given when my baby was a baby
First off (my idea) I never put food into the cage like that. I will always take out the bowl, put the food in and put the bowl back in. Usually this is done fairly early and he can eat at his leasure. Now I do sometimes for treats but he no longer deems me a threat.
Now these were what I felt at the time some working tips that really helped me with my squirmy little guy.
First, remember he is very afraid of you and just trying to defend himself. I would go in there and change water, clean, mess around in there so he got familiar with me doing things. For the first week or so I did not really mess with him. Tegu's learn very quickly. Then I would just rest my hand in there and let him come to me and lick me all he wants and my hand would stay steadily in there. Next phase was to pet, I would put my hand in there, let him come up to it and then I would slowly lift and pet, he would breath heavily, puff, all kinds of good stuff but let me do it I would keep on doing it whether he was doing that or not, then I would simply stop and leave. Everyday got easier.
In his third week I started up baths again, daily baths around the same time. The key with mine was not to hold him too tight, the tighter I held him the more panicked he would become. If I loosened my grip he would not freak as much. I found it was easy to do while standing there but not walking around as he panicked and the tendency to just grip him was strong. I decided to hold him to me, that way he was near my body for support yet my hands could dictate how hard I was holding on. This worked out very good for the both of us.
I had received a lot of suggestions to also let him run free a little in the bathroom and I just sit there. Most of that was fine, he would come up to me, check me out, but when it came time to pick him up he got all ansy again trying to defend himself, tail whipping the whole bit. So instead, when he was done with his bath, usually after he pooped, I would carry him back into my room and let him roam on my bed for a while. This seems to work out very well. He was comfy and I just let him roam, amazingly he didn't try to get off, he would come around to check me out and all was fine, even when it came time to put him back in.
All of this takes time, patience and consistancy. I hear that Columbians can get just as tame if gotten as a baby. And they are very smart as well.
My baby has grown so fast, its amazing.
I really adore him
Hope this helps.