How to select parts by name or properties (programmatic selection)

[dl08in]

I'm trying to figure out a method to programmatically select a specific part or group of parts within an assembly using a VBA macro. The parts are all similar in type, but the part numbers vary from one assembly to the next. (part number = part file name) For example, there is a frame with four sides. The design of the frames are the same, but the part numbers and dimensions of the structural members vary from one frame to another, but there are always two sides, a top, and a bottom. I would like to reference the parts relative to their positions to select either the side tubes or the top/bottom tubes regardless of what their part numbers or instance IDs are. Does that make sense? Is there a way to do this without graphically selecting each part with the mouse?