Great SOAP tutorial here.
LiveJournal's protocol handler here.
It should be pretty straight-forward, but since XML-RPC already escapes return values, and since the LJ protocol handler does already (URL escaping things that could be multi-line... like the "event" in "getevents"), then the wrapper would have to unescape the LiveJournal encoding first, then let SOAP::Lite re-encode it.
While you worked on this, you could make it work first proxying the requests to log.cgi.
That'd be neat.