Press your boobs and push your pelvis tight against his body.
If he's really into you , He will give you a quick kiss on your neck . While hugging I love it . Than he compliments my perfume .
Dress in something with a lot of cleavage and use a push up bra. That why is is more likely to notice your breasts pressing into him. It will also give him an eye full, before the hug so he will already be thinking about your breast, before you hug him.
Press your breasts against him for longer than normal , also rub your crotch against either his groin or hand, depending on the position you are in.
Seductive hugs usually involve some form of assgrabbery.
I would tend to agree with the user below. As you hug him, brush or push your pelvis into his crotch, that will get his attention.
idk maybe brush his thigh/but/crotch area or press your boobs up against him "accidentally"?