Dynamically created menu's are perfectly possible using a cominbation of $iif $style $submenu
The following code will show a submenu 'on channels' in every server or channel window, and lists all the channels you're currently on that the relevent network, selecting one will change focus to the channel, don't know if that's what you want, but it gives you an idea.
menu status,channel {
on channels
.$submenu($onchans($1))
}
alias onchans {
if ($1 isnum) return $chan($1) : window -a $chan($1)
}
