Apache mod_rewrite frustration

Dear lazyweb, I'm having severe issues with Apache's mod_rewrite on my VPS. I'm pretty sure what I want to do is doable, but I can't figure out the rewrite rules to allow it.

In my httpd.conf I have something similar to this:

<IfModule mod_dav.c>
    LimitXMLRequestBody 131072
    DavLockDB /var …
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