Blosxom's amazing flavour support makes it easy to render blog data in a variety of formats. I've built a little Blosxom Flavour for RSS 0.91. Just unpack it in your Blosxom entries folder, then access it like any other flavour with
?flav=rss091 or /weblog/index.rss091
Blosxom has a built-in RSS mode already; the difference here is you have control over it via flavours. I took the opportunity to make the output smaller and to remove the <description> content. See for yourself.