Orientation axis to rotation

Hello all,

I have the orientation axis of a sequence of linked bones and I want to inserted to my 3d model. Does anyone know how I can insert this info to my model? I can use either the local axis or the global axis (I have both info for each joint). I am just concerned if I should convert them to rotations and then apply them (please tell me how) or if I can insert the info of the axis as it is. What is the best way to do that?

Please let me know if something is not clear on my question...

Thanks!