I'm not so sure what you exactly want
But I hope this will help you
.....
POINT pt;
pt = MAKEPOINT(lp);
GetyourCoordinateFunction(...,&pt,...,
DoYourStuffFunction(...,pt.x,pt.y,...,
You can extract the x and y coordinates from LPARAM
variable such as lp by using the Macros:
LOWORD(lp) equals...