Well, from looking at your links (and the rest of your very nice site) I think you might want to re-think that script you are using.
While it would be a good “learning excercise” to get it to work, and that is certainly worth something, I suspect that some of the material your clients will be uploading will exceed the DreamHost PHP max_upload_filesize_limit of 7 MB (hi-res photos and/or video).
To avoid this, I highly recommend uber uploader. This not only seems to meet your needs particularly well, but it has been installed and operated on DreamHost without problems. It also eliminates the need to change anything in the DreamHost environment to upload huge files.
In addition, there are several threads in these forums dealing with uber uploader and providing tips for installing it correctly, which can be helpful if you run into problems.