Yes, it is possible to store the cgi-script (fom) on another server.
Here is an example for a config-file. Note that all urls are given
as absolute ones. Also $useServerRelativeRefs is set to "true",
$serverBase was left blank.

This config works, due to the fact, that both domains, cgi- and 
"normal"-domains, are on the same server but in different accounts.
I dont know if this also works if there are completely separated servers for 
cgi- und htmlfiles (maybe fom will be confused with the directory-vars...).


------------------------------------------
package FAQ::OMatic::Config;
$RCSargs = '-l -mnull -t-null';
$RCSci = '/usr/bin/ci';
$RCSuser = getpwuid($>);
$adminAuth = 'EMAIL@YOURDOMAIN.DE';
$adminEmail = 'EMAIL@YOURDOMAIN.DE';
$antiSpam = 'cheesy';
$authorEmail = '';
$backgroundColor = '#324C69';
$bagsDir = '/home/path/html/faq/bags/';
$bagsDir_Old = '/home/path/html/faq/bags/';
$bagsURL = 'http://faq.YOURDOMAIN.DE/bags/';
$cacheDir = '/home/html/faq/cache/';
$cacheDir_Old = '/home/html/faq/cache/';
$cacheURL = 'http://faq.YOURDOMAIN.DE/cache/';
$cgiURL = 'http://a-different-url.DE/cgi-bin/fom';
$compactEditCmds = '';
$cookieLife = '3600';
$crontabCommand = '/usr/bin/crontab';
$dateFormat = '24';
$directoryPartColor = '#EEEEEE';
$editCmdsDefault = 'hide';
$hideEasyEdits = '';
$hideSiblings = 'true';
$highlightColor = '#d00050';
$itemBarColor = '#FFFFFF';
$itemDir = '/home/html/faq/item/';
$itemDir_Old = '/home/html/faq/item/';
$itemURL = 'http://faq.YOURDOMAIN.DE/item/';
$language = 'de_iso8859_1';
$linkColor = '#3030c0';
$mailCommand = '/usr/sbin/sendmail';
$maintSendErrors = 'true';
$maintenanceSecret = '823acbafac2c';
$metaDir = '/path/to/fom-meta/';
$mirrorURL = '';
$navigationBlockAtTop = '';
$nolanTitles = 'true';
$pageFooter = '';
$pageHeader = '';
$regularPartColor = '#EEEEEE';
$renderDefault = 'tables';
$secureInstall = 'true';
$serveDir = '/home/html/faq';
$serveURL = '/';
$serverBase = '';
$showAttributionsDefault = 'hide';
$showEditIcons = '';
$showEditOnFaq = '';
$showLastModifiedAlways = '';
$showLastModifiedDefault = 'hide';
$showModeratorDefault = 'hide';
$statUniqueHosts = '';
$tableWidth = 'width="100%"';
$textCmdsDefault = 'hide';
$textColor = '#000000';
$useDBMSearch = 'true';
$useServerRelativeRefs = 'true';
$version = '2.712';
$vlinkColor = '#3030c0';
1;
------------------------------------------

Good luck!