Welcome Jan!
Unfortunately, not many developers visit here. (something which I hope to change in the not too distant future) And that is a developer type of question!
The best place to get help would be the developers mailing list.
http://lists.sourceforge.net/mailman/listinfo/inkscape-develOr, there's an IRC channel for developer questions. However, it will be holding the board meeting starting in about 20 minutes, and lasting for an hour. irc://irc.freenode.org/#inkscape-devel
But there's also a user's channel where many developers also participate. So if it is urgent, you could start there. irc://irc.freenode.org/#inkscape Or else, the mailing list, as already mentioned.
Have you seen the resources on the website about writing new extensions?
https://inkscape.org/en/develop/extensions/ And there are some command line info too.
https://inkscape.org/en/doc/inkscape-man.htmlMaybe you could find some answers there too?