httpd-rewrite.conf

RewriteEngine On
RewriteMap pairtree-map prg:/opt/local/apache2/map.pairtree.py
RewriteLock /opt/local/apache2/map.pairtree.py.lock
RewriteRule ^/pt/(.+?)/(.*)$ /pairtree/${pairtree-map:$1}/$2

map.pairtree.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# uses the python pairtree library from github.com/edsu/pairtree/tree/master/pairtree/


import sys
import pairtree

while sys.stdin:
        print pairtree.id2path(sys.stdin.readline().rstrip())
        sys.stdout.flush()