well when i used to own a slim ps2 i used a boot cd/dvd called ‘Swap Magic v3.6’ as this allows you to make copies of your own original games and burn then onto a recordable dvd and then play it on the ps2.
basically what it does is… you power on the system with the swap magic boot dvd in it and it takes you to a menu and after disc stop’s spinning you then remove the swap magic disc and replace it with your backup copy and press X on your ps2 controller and it will boot the backup copy
p.s. only side effect is you need a flip top tray as it need a way to open the tray without the ps2 knowing you opened the drive tray (i.e. the ps2 still think’s your system is running the original)
so basically i had to buy another case (flip top case) and the swap magic discs in order to play backups on my slim ps2.
i got all my stuff for the ps2 from www.clearxbox.com (but i was just checking there and i cant seem to find the swap magic discs there for sale anymore)