hi,
just a note:
EQU is not a declaration; it is the definition. By the other words, when you type A EQU B so it asks a compiler to replace all the A with B like in C-language you use a macro definition. So it has nothing with variables and cannot help you.
Okay, now just a suggestion (not tested yet): declare your variable with BIT keyword, something like LITE BIT P2.1 and then indicate LITE as PUBLIC in file it has been defined, and as EXTRN in anothers which share it - should work? I hope.

cu