Changing Mailspool

I am trying to compile 3.11pre7 (mostly for a learning exercise).  I've 
changed the BASENAME in the Makefile file and changed MAILSPOOLDIR and 
MAILSPOOLHOME early in authenticate.c .  When I compile the program, it 
still uses "/var/spool/user" instead of "$HOME/.mailbox/inbox" as I'd 
hoped.  Can someone point me to where else I need to fix the mail spool 
assignment?  Thanks!