Firefox custom extension installer

i am searching for hours now, a way that could allow me to install (optionally) a custom firefox extension along with my software installation package.. i can't find anything useful tho. Tried the registry method, the -install-global-extension method, the "Copy to extensions path" method... but nothing seems to work.

Any ideas on how to let the user chose if he wants to install my extension after my package install is finished?

You have this tagged "batch" so I'm assuming you are looking for a way to install extensions from the command line using batch format.

What is the output if you were to use something like this?

for %%e in ("path to extensions\*.xpi") do "firefox.exe" -install-global-extension "%%e"

I have an Nsis installer that in one of its steps copies a Firefox extension to the extensions directory. That works for every Firefox version from 3.0 to 4.0.

First it finds out which is the directory for the default profile, following this pattern: %APPDATA%\Mozilla\Firefox\Profiles*.default. Once profile name is determined (for example "4v3vxq80"), it copies the extension to %APPDATA%\Mozilla\Firefox\Profiles\$1\extensions (where $1 is the profile name).

I think the key is that all these steps are performed when Firefox is not running (I check for a running firefox.exe at the beginning). Let me know if you want the nsis code that does the trick.