I just released Slash-Client, which right now is useful only for one thing: talking to Slash sites with SOAP to do journal stuff. I've been using it to post journals for a few weeks.
The base Slash::Client module handles authentication and SOAP stuff, while Slash::Client::Journal is merely a frontend to the SOAP calls add_entry, modify_entry, delete_entry, get_entry, and get_entries.
Read up on authentication in the Slash::Client POD, see the example in t/journal.t, and everything else should be self-explanatory.
Have fun. Let me know if you've got any problems.