I'm not too worried about this right now, as there is such a small linux game market atm anyway. But, there is always the possibility of switching scriptting engines. But, I think the sticking it out with squirrel for now.
I had already though about trying LuaPlus on Linux, as you mention, SqPlus is roughly based off of it. However, I downloaded some source, and it does not appear to have makefiles :/ (I may have got the wrong thing though).