coppermine will not support xcgal as it's heavily hacked..

xcgal is based on coppermine 1.1 which is very old.. i stopped using it because i needed multi upload on the user side.. instead i use standalone coppermine (annoying having to have to register twice, but i put it to my users that they could have 1 or the other at the moment.. either multi upload, or havie to login twice, i knew they'd opt for multi upload) i use cpmfetch to display random images from coppermine in a block on xoops..

the next version of coppermine which should be released soonish i think will have a bridge file for XOOPS so that single login is possible.. it won't be an integration as such just a sharing of userbase and session. but i think that's acceptable (to me at least) and you can use cpmfetch and magpie rss to display images from cpg in blocks and add a recent photo's block too :) wrapping inside XOOPS will be harder tho unless u use an iframe.. but you could add your header to cpg theme anyway, and customise the menu links.