Don't do anything in MyDocs: it's a FAT partition and forgets all permissions. When I did all of the building etc I did it as root in root's home directory.

I've just managed to get around this. I made two files:

/usr/share/accounts/providers/msn.provider
/usr/share/accounts/services/msn.service

by copying the skype ones and changing the fields (harmattan has two different msn icons already!). Then I had to install sqlite3 and add the account in ~/.accounts/accounts.db. I managed to get jabber displaying properly too, but there's no bundled icons for that, so I'll have to make one later.

If I get time later i'll write it all up so others can try.