Does he have any brain damage of cognitive deficits from all the drugs and alcohol?

Can you have a conversation with him and does he understand the consequences of his actions. He sounds like he has missed out on a lot of emotional development. He has yet to build social skills and mature.

Try to explain to him that what he is doing is disrespectful to women. He is not just looking but leering. And that is also considered a form of harassment. Importantly let him know that you find it uncomfortable and that this isn't how men behave towards women. Perhaps you could use the analogy of if he had a sister, or, daughter and watched men doing that to her, how would he feel.

It might take him a while to understand this. You might have to repeat the message.

What kind of staff work at the group home. Can you talk to the therapy team about his behavior. The might have to introduce some behavior therapy.