I am a student developer and I have built several installers for the company I am working with now. So I am fairly familiar with WIX. We recently decided to have a Build server
I had a similar situation where the source path of the files was to be passed as a command line argument to the build script. This is what I did: Edited the wixproj file and added the following content under the "PropertyGroup" node:
where R: is the default directory/path from where to pick the source. Now, the source can also be passed as a command line argument during build:
msbuild /t:Clean,Build "MyPath\MyWixProject.wixproj" /property:Source=MyConfigurablePath /p:Configuration=Release