I just finished making a bunch of code changes. So if you go this route, you may encounter problems. Having said that, feel free to email me or the pyblosxom-users mailing list with questions. It should be noted I'm posting this entry with w.bloggar right now.
Make sure you have the latest CVS codebase
Read the top of xmlrpc.py and set up the right config.py parameters
The w.bloggar account settings should be as follows:
In the Content Management System section:
Blog Tool: "Custom"
In the API Server tab:
Host: the name of your server
Page: the url of your blog with /RPC at the end (mine is /~willkg/blog/RPC)
In the Custom tab:
Posts: "Blogger API"
Categories: "Not supported"
Templates: "Not Supported"
Title Tags: (make both fields blank)
Category Tags: (make both fields blank)
When you go to write a new entry, leave the title field blank and do your entire post in the data section with the first line being the title (just like blosxom entries).
One thing you should note is that pyblosxom will take the first line and use that to generate the file name of the entry. So if the title of the entry is "How to use w.bloggar with pyblosxom", the file name ends up being "How_to_use_w_bloggar_with_pyblosxom.txt" which is a little annoying but whatever.
That seems to work for me. Poke me if you have questions and I can update this entry with the adjustments.