I didn't remember if Chris had said he hadn't figured out how or if it was just not clean, but this seems to have accomplished it in a relatively clean way:http://blogs.msdn.com/jomo_fisher/archive/2005/04/22/410903.aspx
At least I just tried it and was quite happy with the results.
Edit: Make sure to have 'Smart Device Programmability' included on install so you get the Compact Framework assemblies. It relies on some tasks defined in Microsoft.CompactFramework.Build.Tasks.dll, which could live elsewhere, but I wasn't sure.
Also, posting links in this system isn't so much fun.