yes, it's due to the fact that in order to define third degree of freedom(roll) you have to specify third point in coordinate space. unfortunately, gamestudio doesn't have a predefined function for this, so you'll have to deal with underlying math to implement it. however, if you're willing to make some kind of ragdoll system (just my guess), you won't need this anyway.

as for quaternions - one forum member has made a neat tutorial, explaning how they work and how to implement them (it was either Joozey or JibbSmart if i recall correct), just search for it.