Another possible answer (or set of answers) for those of you with the "blank page" problem (my summary below applies to Fedora Core 3).

1.
The blank page problem can occur when [your_path]/install/index.php fails on line 349 which attempts DB connection via the dbm object via the following syntax: $dbm->isConnectable()

2.
After wasting a lot of time trying to debug XOOPS install doe which probably was fine anyway, it occured to me to make a very basic script to test PHP connection to MySQL, which looked as follows (your path to PHP as listed on line 1 of the below may vary):

#!/usr/bin/php
<?php
$link = mysql_connect('localhost', 'apache', '4p4ch3');
if (!$link) {
die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';
mysql_close($link);
?>

3.
After creating above script, run chmod +X your_scriptname to make it executable

4.
Then run ./my_scriptname

5.
If your test script returns an error, locate your php.ini and make sure the line extension=msql.so is uncommented (it is commented by default).

6.
run rpm -q php-mysql from command line to verify php-mysql support is installed - if not see sysadmin or google for how to install RPMs/updates

7.
Make sure to restart apache following php.ini changes and package installation.

8.
Your test script should now work - if so, you'll probably be able to get through the XOOPS installation wizard without the dreaded "blank page"