Changing the module path on custom install profile
You can get an example in Videola profile:
https://github.com/Videola/videola/blob/master/videola_starter.make - main make file which downloads only profile from github.

Then see main make file with all the modules: https://github.com/Videola/videola/blob/master/videola.make which shows you an example of what you want to do.

projects[admin][subdir] = "contrib"