That's 16 colours in SuperPlus 800x600 screen mode. I don't think 256 colours are usable on a600. 16 colours needs a lot of power.
It's simple to install. Use winuae with Aga settings to install. Disable loading screen in S-S, change resolution to super plus 16 colours, in WB startup disable clock. Rename system partition to Amikit and reboot with ECS selected as chipset. Should work. Than disable things you don't need and use ACATune to speed up system little bit. You need to install on PFS and have ACA630 and flashed Indivision ECS.