After installing XRMS on a debian system today, I came across the issue where PEAR is not installed and so I need to manually edit QuickForm.php to get it to work. I have created a patch for install.php which checks to see if it can load PEAR.php, if it fails then it will use a regular expression to automatically update QuickForm.php to use $include_directory.'classes/PEAR/PEAR.php' rather than PEAR.php.
If the webserver user doesn't have permissions to update the file, then it displays a warning explaining the issue to the user and providing details on howto manually change this.
I know this info is in the README file, but I think this maybe a better solution.
This patch has only been tested on my Debian box, running Apache2 (running first as root, then with reduced privileges) and PHP5. My patch defines a function which should ensure it works with older versions of PHP.
This could do with some more testing on other setups, hope its useful.