Actually, I easily succeeded into making both of them working together. Since you can't hook directly into MyNetwork's code - or you can, but not as you are used to - you have to insert admhijack template codes manually into your MyNetwork's templates. The code you have to insert manually is the following:
I wouldn't recommend putting it into MYN's member_profile template just because admhijack_profile() function can't be hooked and consequently loaded within MYN. Since that function does nothing than a "Is moderator?" check, I suggest you to put those few lines of code into MYN's member_profile_modoptions or even better member_profile_adminoptions templates, performing the moderator (or admin) permission check by default.