Jeff,
Would it be possible to instantiate the portfolio package using the portfolio.info file via callbacks? I'm not sure which event would be appropriate to do this...
before-install
after-install
before-instantiate
after-instantiate
before-mount
after-mount
To me the instantiate and mount events are the same, but there must be some difference that I don't know of.
Once instantiated, the portfolio-admin package can be mounted at different URLs.