Ouch! There's nothing there that can't be done, but that doesn't necessarily mean it should be done.
The combination of register_globals_on and allow_url_fopen is particularly dangerous and, as such, is probably not suitable for use on a shared server where other users can/will be impacted if your site is exploited, IMHO .
Dreamhost set those setting's "off" for good reason, and changing them assumes a huge responsibility; you may be introducing significant security vulnerabilities to your shared server by running a script, or scripts, that rely upon those settings. There is a little more discussion of that aspect of modifying your PHP environment in this Forum post.
I'm sorry, I'll have to pass - I just don't have the time to undertake a thorough "vetting" of the script involved to determine how secure it is (and make any necessary changes), which I would feel obligated to do if I made this change for you. Hopefully, you can find a "crack" PHP programmer you can hire to do it properly, as opposed to just retaining someone to change the PHP environment for you without making certain it is safe to do so.
Have you inquired as to whether the support staff at the company that sold you the script are willing to undertake this for you? It would seem they would be the obvious place to start, as no one is likely to know and understand their script better than they do.