Using the domain mapping plugin with a subdirectory install that's in a subdomain

I'm wondering if it's possible to use the domain mapping plugin with a subdirectory install of WPMU that's located in a subdomain.

So say I have a WPMU install located at http://myinstall.mydomain.com/ with blogs at http://myinstall.mydomain.com/blog1 etc. Will the domain mapping plugin work with this setup? My suspicion is that it won't, based on the plugin documentation. Thanks in advance.