Dunno how I missed that thread... Looks like I've wasted my time explaining the whole procedure to a couple people here since then, when I could have just linked to it. It's going in my bookmarks right now.
I don't think having a Mac should change anything as outlined in the first couple posts of that thread, because that's all done within the browser. If Safari can't do it for you, I'd suggest getting a copy of Firefox. The photo resizing isn't done via the browser though, but I'm pretty sure that iPhoto should be able to take care of it for you.
For all the nonsense about Macs being idiot-proof, easy-to-use, and "reliable" (LOL), every time I encounter one they throw a wrench into the gears because they aren't made to work with anything else BUT a Mac. Maybe I just have crap luck but they sure haven't given me a good impression over the years.