I have written a python script, which uploads usermaps defined in Excel to MF Connect. This is currently only supporting a 1:1 system mapping, while as a usermap could include 1:n users. 
The script is on Github, in case someone need to change it. https://github.com/a1m0ctane/mf_connect_import_usermap A short presentation and a youtube video: https://www.youtube.com/watch?v=zCMGGp2Svk0
Feel free to share.
Enjoy!