I don't know much about hotkeynet. I personally use keyclone, which basically replicates keypresses.
If I press the 1 key on my keyboard, it broadcasts the 1 key to each of my clones (along with my main screen).

My 1 key can be whatever is there.
In my case its cast spell 1 for the main toon.
For the other windows its assist main toon and cast spell 1.

There are a lot of ways to set up your basic assist. The wiki is a great resource.
The basic methods seem to be...
Assist main toon with slave toon and cast.... good for two boxing or small number of toons.
Have all toons make one of them their focus, and then cast at the focuses target.
Cast at the party leader's target, with all toons (basically paging your action bars, to free up the /focus ability).
Keystrings to auto determine which toon is the lead and have the others assist them... not sure if this can be done without keyclone.

Not exactly sure what you're asking, having never used hotkeynet.
Search and the wiki are your friends.