I do it this way after starting perl -mCPAN -e 'CPAN::shell':
o conf makepl_arg arguments
install package

So in your case you might write a script to start Perl as above and then feed in:

o conf makepl_arg --perl_only
install version
[download]

I've done this with an automated installer that uses the GD module (which requires -options JPEG,PNG,GIF fed to the makefile) and the libwww-perl module (which required -n to be fed to the makefile).