First off... "Cage dominant" is not actually a thing. Sure, a cham may puff and hiss and lunge when you mess about in his cage, but "cage dominance" is basically a catch-all phrase which does not adequately describe behaviour and often leads to misinformation. "Territory dominance" is a thing, where an animal seeks to drive out individuals that compete for valuable resources, but I would argue that it does not apply to chameleon-human interactions as humans are 1) not chameleons and 2) do not compete with chameleons for resources. I'd argue that a cham who is hissing and puffing about having a human in their space is... just not comfortable having a human in their safe space, not trying to drive them away to guard their cup of bugs! Terminology matters
Otherwise... it takes
time to earn trust, no matter what species. Act in a trustworthy fashion: don't stare, loom, etc. Move slowly and predictably. Offer the hand-feeding bugs at the same time every day. Start a routine and stick to it. Reserve his favourite foods for handfeeding, hold them out very very steadily for a few minutes. If he doesn't take them, but them in his feeding cup (or wherever) and walk away. It took months for my roomate to earn my panther chams trust, but now she can move him around the apartment no problem. At the lab, it can also take a significant amount of time before the chams get used to a new caretaker.
Keep in mind that some chams are just more wary than others. Some may never be comfortable being handled much, but I've yet to meet a cham that wouldn't calm down at least a little- maybe not enough to be handled comfortably, but certainly enough not to freak out over minor cage maintenance.