Ok,

Uploading is how I did my customization - four folders (to 1.5.4): installNew, installChanged (added my code to affected 1.5.4 files), adminNew, adminChanged (added my code to affected 1.5.4 admin files).

Whoever wrote those modules didn't use Zen Cart database access methods....

Someone will need to rewrite those (polish?) database query calls....
Thanks for your efforts - it's currently a bit out of my league! I could (try to) arrange for a moneybookers merchant account for testing purposes!?

BTW: The process don't seem that secure!?