AutoCAD 2013 :: Using Alignment Parameters

I have what I believe is a good use for block alignment parameters, but I'm having trouble getting it to work the way I want. Let's say I am building a space frame. I start by drawing a series of 3D lines from one node of my space frame to another which defines the center lines of each member of the frame. Then I have a block representing a tubular member of the space frame. I would like to add an alignment parameter to the block such that I can insert a member and align it to one of the 3D center lines. Preferably, I should be able to insert and align in a single step, although it would also be fine if that were two steps. For example, I could first align the block to one of the 3D lines, and then move the insert point of the block to a node point of the space frame. 

I am able to create an alignment parameter on my block, but I find I cannot use it to align to a simple 3D line. It will align to the edge of a solid without problem, but not to a 3D line. 

My alignment parameter is (I believe) inserted at the insert point of the block. Although, in the Block Editor you cannot seem to specify the insert point directly. Perhaps because I am editing the block its insert point is not available in that mode?