my usb is now ready to use. ^^
i made some photos that might help you, if you want to upgrade, too.
but be warned - it's no beginners task, the ssop28 is very tiny

maybe you should practise on some broken devices first, i did so! ^^
you will need a gamebit or whatever to open the cart - or torx E4
the back-shilding has 2 philips-head screws
in my case i had to alter the shilding so it fits better and don't "sit on" the ed64 pcb
the location of the mini-usb-port
the location of the ft245rl.

my hint is to watch some yt vids first on how to solder such parts manually ^^
the hole for the usb-jack must be big enough, 'cause the port sits somehow deep inside the cart. ^^

my finished work


i printed a cover, too. it's from labels.arcade-tv.de and can be downloaded as a ready to print pdf

greetings, saturnu