redirectorater is a non portable utility designed to be of use to people who regularly use portableApps on the same computer. You install redirectorater to your local PC and associate file types with redirectorater.exe, then redirectorater will look to see if the portable application exists, and will launch using that if available. If not, it will launch the app using a local application.
For example, .txt files could be associated with redirectorater, which can be configured to launch Notepad++ if it is available, but fall back to notepad on the local pc if the portableApp is not present.
The .ini file for redirectorater includes the drive path of your portable drive, so if you are running a menu mod that supports autolaunching, you could write a utility to update the settings on execution. If your drive always runs as the same letter, this would not be necessary.
Here is a quick sample INI file for associating zip files with 7zip portable, falling back to native windows zip support:
Download redirectorater here. Please note that the included redirectorater.ini must be edited to point to the appropriate portable drive (and you probably want to remove my file associations from it as well.