install.packages parameters

Hello.

R is having some trouble installing a package because it passed arguments to 
gcc which were non-existent directories and files.  It also didn't find 
g77, although it's in a directory in my $PATH;  I tricked it by making a 
sym link in /usr/bin.

What file does R get these parameters from?  
I've looked for the parameters in the package source, the install.packages 
help pages, and the R preferences menu, all to no avail.

I am running R 2.1.0 on Mac 10.3.8, and three days ago I installed a
different package from source where installation involved gcc without
any problems, and nothing has changed since then.  The packages I'm
trying to install are Joe Schafer's mix, norm, and cat.

Thanks,

Janet