I am looking for the hotkey combination for our HP 336044-b21 KVM switch from a iogear KVM?

IOGEAR KVM switches uses Scroll Lock for the hot key. The models of IOGEAR KVM switches starts the letters "GCS". I don't think that your HP 336044-b21 came from IOGEAR.

Anyway, if that's an IOGEAR KVM switch, you may quickly press Scroll Lock twice + Enter (for two port KVM).

Scroll Lock twice + port # + Enter (for 4 port, or 8 port KVM).

NOTE: You need to verify the brand of your KVM switch by referring to the user manual of it.

Thank you and good luck!