On PHP5.x you can't even install Xoops Cube. I tried to do that with both stable version and svn trunk in vain. I got too mad to post a patch.
(1) When a function of a class calls it's parent class constructor and the parent class does not have a function which name is the same as the class name, like constructor on PHP 4.x, it must be like 'parent::__construct'. Otherwise some functions of Xoops Cube are calling their parent class constructor by 'parent::parentClassName', It cannot work at all.
(2) parse_ini_file function causes fatal error when a file assigned as an argument containing PHP tags like '<?php' nor comment block identifiers like '/**'. That's exactly what some *.ini.php files of Xoops Cube are, and you see those fatal errors in your install process.
The attachment is a combined diffs that 'svn diff' command spit out. Fixes for #2 is a bit too weird, so please give a double check in use.