And again I had to create and copy some stuff because I want to run it as my normal user like I also do with MPD.
Here's the way how I've made it work:
Mpdscribble <=0.21 has a small bug and doesn't work with >=curl-7.21.0, so the curl useflag needs to be disabled in /etc/portage/package.use:
Unmask the most recent version v0.22 in /etc/portage/package.keywords:
Create the needed directories in your user home:
mkdir -p ~/.config/mpdscribble
Copy the config file from /etc/mpdscribble.conf to ~/.config/mpdscribble. You need to be root for doing so because the config file is only readable as root.
sudo cp /etc/mpdscribble.conf /home/<your user>/.config/mpdscribble/
Edit the config file ~/.config/mpdscribble/mpdscribble.conf but take care to use full pathes:
pidfile = /home/<your user>/.config/mpdscribble/mpdscribble.pid
log = /home/<your user>/.config/mpdscribble/mpdscribble.log
verbose = 1
url = http://post.audioscrobbler.com/
username = <your last.fm user>
password = <your last.fm password>
journal = /home/<your user>/.config/mpdscribble/lastfm.journal
Everything else is commented out.
Now you can start mpdscribble:
mpdscribble --conf ~/.config/mpdscribble/mpdscribble.conf