Development: Moving local images into G3

As I wrote in http://gallery.menalto.com/node/103803, I am currently using the REST API to move a file into G3, but it is too slow (so the client app times-out after it uploads the file to the server and waits for the REST API to move it into G3). Since the file is already "local" (on the same G3 server), I need to figure out how to programmatically move it directly into G3 and retrieve a link by which the client can access the item (similar to or exactly the same as the REST API does). I know this sounds odd because the REST API allows me to upload directly into G3; but the app requires that the client be insulated from G3 particulars. So I think I need to write a G3 plug-in. As with everyone else, I need this done "yesterday", and I am just now getting to it.

I am looking for some quick pointers to help me hit the ground running. What should my conceptual approach be? Are there APIs that I can use, directly? What parts of the code should I be looking at or what plug-ins (if that is the approach I should take) should I look at, as an example? I'm trying to access the google doc posted in the sticky (https://docs.google.com/document/pub?id=1DQ1Tz177aX5ZsSgEbjYtYOBufJ0SYhgYvfJtA6snn2Y — I am currently having trouble accessing the doc, but I assume I'll sort that out (problem at Google?)

Thanks for any guidance you can lend,
Bill...

(Perhaps, there should be a separate forum for G3 Development and developer issues?)