Honestly, i wouldn’t have the slightest idea where to start. I tend to look at the code and go from there…
As a side comment/query, have you considered the security implications of adding posts from the front end… there’s a reason this stuff is usually put in the backend and why some sites that have frontend management features are sometimes subject to exploit… examples could be facebook, twitter, myspace ..
I’m not saying it’s something you should’nt do, …. however it could possibly become a support nightmare for you if you’ve not had a great deal of experience with this type of scripting before.
I’m not sure it’s really suitable to direct you there, but it may be worthwhile dropping your query onto the hackers mailing list, to see if anyone there can offer some suggestions/alternatives for your initial question..