Welcome! Fully customizable screen modes only exist under OS2.x or higher. For 1.3 you have just the choice between normal (640x256 for PAL) and interlaced (640x512).
The config tool may require 2.x or above - I'm not certain. The only important option in it is whether the Indivision should also tweak the vertical refresh to be compatible with LCDs that can't do 50Hz. The other options are just minor preferences.
Getting the tool to your Amiga is the same as getting any other file to your Amiga, although if you've never done it before it can be a bit of a chicken and egg problem. Serial link with Cloanto's Amiga Explorer is my recommendation. There are hardware solutions that can give you a CompactFlash slot internally or externally, replacement floppy drives that use adf disk images, and I think there are some hacks to write Amiga floppies from PCs now, although I might be remembering that wrong and they're read-only.
