Running PHP as an apache module (DSO) poses a large security risk in a shared hosting environment, as it would allow you to read everyone else's files on the server, which is why we do not and will not ever do this. Second, in order for php as an apache module to actually write to stuff, directories and files need to be marked as world-writable, which means that not only will other accounts be able to READ your files (like your database username/password), but they'll be able to WRITE them as well (such as installing illegal scripts on YOUR account)... I'm sure you wouldn't want that to happen, would you?
Additionally, this means that your directories should NOT be world writable, so go ahead and change ALL of your cache directories and stuff from 777 to 755, trust me they'll work just fine.
If you find you can't install that script, then find one that isn't poorly-written because no well-made script should be dependent on what kind of php is running on the server.