The translation transformation is relatively trivial and only included for completeness; for a translation, you may find it easier to use mapcar, for example, the following expression will translate a given point by the vector '(1.0 2.0 3.0):
(mapcar '+ <Your-3D-Point> '(1.0 2.0 3.0))
To determine the insertion point of a nested block relative to that of the parent block reference, you will need to construct a transformation matrix which accounts for the position, scale, rotation & orientation of the parent block reference, and then apply this matrix to the vector between the origin of the parent block definition (which is usually 0,0) and the insertion point of the nested block within the parent block definition - you will find gile's refgeom function useful in this respect.