There may be other settings that also affect directory structure, but the 2 most familiar to me are as follows (http://search.cpan.org/src/JHI/perl-5.8.0/win32/Makefile):

#
# Comment this out if you DON'T want your perl installation to be vers
+ioned.
# This means that the new installation will overwrite any files from t
+he
# old installation at the same INST_TOP location.  Leaving it enabled 
+is
# the safest route, as perl adds the extra version directory to all th
+e
# locations it installs files to.  If you disable it, an alternative
# versioned installation can be obtained by setting INST_TOP above to 
+a
# path that includes an arbitrary version string.
#
#INST_VER = \5.8.0

#
# Comment this out if you DON'T want your perl installation to have
# architecture specific components.  This means that architecture-
# specific files will be installed along with the architecture-neutral
# files.  Leaving it enabled is safer and more flexible, in case you
# want to build multiple flavors of perl and install them together in
# the same location.  Commenting it out gives you a simpler
# installation that is easier to understand for beginners.
#
#INST_ARCH = \$(ARCHNAME
[download]

MJD says you can't just make shit up and expect the computer to know what you mean, retardo! I run a Win32 PPM repository for perl 5.6x+5.8x. I take requests. ** The Third rule of perl club is a statement of fact: pod is sexy.