It is not possible to make cables work with microblocks without having IC² dependent on RP. About luminators in the cable's block... If it's possible, I like it! Also, what about glowing cables like IC1-luminators?
Yeah, I'm not really sure how the code works. It seems the cables are already physically smaller than a full block but you still can't place anything within the same block space. It's a shame really because microblocks are an excellent idea and really add a lot to the game. Perhaps Alblaka could collaborate with Eloraam to incorporate microblocks into IC2? These developers are coming up with some awesome things on their own, imagine what they could do it they worked together!!