<p>I know I've seen this in the past, but I can't seem to find it now.</p>

<p>Basically I want to create a page that I can host on a <a href="http://www.codeplex.com/dasblog" rel="nofollow noreferrer">dasBlog</a> instance that contains the layout from my theme, but the content of the page I control.</p>

<p>Ideally the content is a user control or ASPX that I write.  Anybody know how I can accomplish this?</p>

I did something similar setting up a handler to stream video files from the blog on my home server.  I ended up ditching it because it killed my bandwidth whenever someone would view a video, but I did have it up and working for a while.
To get it to work I had to check dasBlog out from source control and open it in visual studio.  I had VS2008 and it was built using VS2005, so it took some work to get everything to build.  Once I could get the unaltered solution to build I added a new class library project to hold my code.  This is to make sure my code stays separate across dasBlog updates.
I don't have access to the code here at work so I can't tell you exact names right now, but if you want your pages to be able to use the themes then they need to inherit from a class in the newtelligence.dasBlog.Web namespace, and I believe also implement an interface.  A good place to look is in FormatPage and FormatControl.