Msdeploy: Replace provider attribute values during deployment?

Question

Msdeploy: Replace provider attribute values during deployment?

I have an msdeploy question on how to replace attribute values for providers in the source manifest during deployment.

Story:

I use msdeploy to create deployment packages during assembly release. I want the packages to be deployable for testing / staging / production and should be able to change deployment times. One of the things you need to do during deployment is to create message queues (msmq), something that msdeploy does not support out of the box (technically you can use a script and use msdeploy, but this is not fun). I created a custom provider for msdeploy that allows me to create these message queues during deployment (msmq). Which queues to create and some settings about them will be indicated in the sourceManifest.xml file, which looks something like this:

<sitemanifest>
  <msmq path=".\private$\some.application/SomeService.svc" isTransactional="True" shouldGrantNetworkServicePeekWrite="True" userNameToGrantFullAccess="testdomain\username" />
  <!-- more (non-relevant) stuff here -->
</sitemanifest>