I am also thinking a separate control for the IK stuff would be best, but it needs a lot of information about the animations. E.g. on some animations you want to have IK (dance, idle, run, walk, ...) and on some you don't want to have it (like flying, jumping, falling, ...). And this ofc also depends on which animation is currently playing, with which weight (transition between jumping and walking might mean only 0.5 of the IK placement should be applied).
Edit: And also the masks ofc
Do you think to set all the additional information up in the IK control and then observe the events of mokanim would be the best integration?