-profile option

How can I use the -profile option to point to a user profile. In "normal" thunderbird I just write -profile [file path/name].
Can I do this with the portable thunderbird launcher? If so, how? Creating a shortcut includes the drive path, which would ruin the portability, as a different machine might mount the drive on another letter.

The .ini file could remove the restriction that the path is relative to the launcher directory *and* must be a subdirectory of the install directory. I tried using ..\ in the .ini profiles line, but that didn't work, guess it really has to be a subdirectory like it says.

Alternatively, while I haven't looked at the source, but conjecturing how the launcher works, it may be possible to have the launcher look for a file in the same directory as the launcher with a name like "profile", which would contain the file path (relative to the launcher) for the desired profile. The launcher would then append this to the exec command that launches the actual app.

Thanks.