calibre-cutomize with portable Calibre

[pandako]

I'm trying to develop a Calibre plugin against a portable Calibre installation. That is, the one available from here: https://calibre-ebook.com/download_portable

Loading my hello world plugin by ZIPing the directory and using the Calibre UI works, but using the calibre-customize tool doesn't.

It seems that when I do

G:\path\to\portable\calibre\Calibre\calibre-customize.exe -a helloworld.zip

or

G:\path\to\portable\calibre\Calibre\calibre-customize.exe -b devfolder

they seem to copy the plugin to %appdata%, instead of the portable location. There doesn't seem to be any options in the "-h" page to specify a custom path either.

Can people teach me how calibre-customize can be used with a portable installation?

[pandako]

Solved it myself after reading the CPP code for the portable executable! (here)

It just needed to set an environmental variable first.

Here's a snippet from my final batch file.

SET "CALIBRE_CONFIG_DIRECTORY=G:\path\to\portable\calibre\Calibre Settings"
G:\path\to\portable\calibre\Calibre\calibre-customize.exe -a helloworld.zip
G:\path\to\portable\calibre\calibre-portable.exe