Ease of Custom Mounted Units

(Not sure if this is general modelling or model-editing; either will do, really)
(Also, this isn't a request; however, depending on how it's resolved, it might lead to one.)

Alright, I've always been plagued by mounted units in my works; they're really cool, but I've always had to attach a unit to another. And of course, that always leaves the attached unit (mount or rider) sans animations; a stiff mesh (except when the other unit isn't moving).

So I would like to know, roughly, how difficult it is to "mount" a pair of units and each have them use separate animations. Is it "anyone with Magos/Oinkerwinkle's can do it" easy, or more like "you'll need the help of a good modeller/animator"? Basically, I've got at least 3 models that need this; I'd like to learn how to do it myself, but is it feasible to make it/them a request?

(Also, I know you're helping dust, but I wanna get the general consensus; perhaps this isn't as big a deal as I make it seem?)

Any help would be appreciated.

well, the problem i would see is that you'd have two sets of animations which have nothing in common...
(as the keyframes starting and ending an animation will most probably not be the same that even becomes worse)
so i guess you'd need to remake the mounted unit's animation
(that's what i would do in max, dont know about geoset editing and stuff)