Hello, amarok currently has a dcop call to get the url of the album cover. I could not find one to set an album cover though, I think it would kind of useful, for me at least. Or is there a way I can set it through commandline somehow without dcop?

Not currently, but you could submit a wish bug report.

The closest thing would be using the EmbedCover script, which puts the image right into the ID3V2 tag. This only works for MP3, though.