[R-sig-hpc] Makevars.in - changing compiler

[George Ostrouchov]

Is it possible to set a package compiler via Makevars.in? I need to 
substitute mpicc (an Open MPI wrapper compiler). My attempts just 
setting CC=mpicc in Makevars.in have failed.

Is Makevars just "included before the default `Makefile'" as it states 
in the "Writing R Extensions" manual or is there more to it?

Thanks,
George