Problems with pkgsrc or compiling PostgreSQL

Hello.

I want to have postgresql82 on my NetBSD 3.1 sytem (running on an alpha 
system). There was no real problem to get it on my system. Jump 
into /usr/pkgsrc/databases/postgresql82, doing make an make install, finding 
how to start at boot time et voila, it's running nice.

But then I found out, that the language plpythonu could not be created. Even 
not after make;make install in /usr/pkgsrc/databases/postgresql82-plpython.

I found my problem as I do not know how to set options for the make process. A 
hopeless -Dplpython was not successful. I have gone through the pkgsrc 
manual. But when I tried the shown possibility to find out about options the 
makefile says: Not options supported.
In the file Makefile.common I found the line:
CONFIGURE_ARGS+=    --without-python

Here I think the problem is, but how to resolve? I even tried to comment out 
the line in the Makefile (with bad feeling in the stomach as I do not think 
Makefile editing is the right way). Also a -Dwith-python or a --with-python 
does not help. So I'm sitting around with a nice database management system, 
but without my functions it is not even half of the fun.

After a search through the internet (at least some part of it) it seems to me 
that I'm the only one with this problem.

But to cut the long story short, two questions:
1. How to compile python support into postgresql?
2. Am I on the right way to solve the problem or missed I some important 
source around postgresql an NetBSD or the pkgsrc-system on NetBSD?