I want to change some options in my php.ini file but I want to keep all the other PHP options the same as DreamHost. I know to accomplish this I will have to follow the Advanced PHP configuration wiki page that DreamHost has. If I later decide that I no longer want to use my custom setup, can I delete all of the custom PHP files and the domain will revert back to using DreamHost's install?
It sure will. Once you revert the .htaccess, the server will use the default PHP configuration.
And you're planning on just the php.ini mod, right?
Yes, I just want to change some options in the php.ini file.