1. Just install them with TSM. That should install a directory called 'tracks' in your main GP4-directory if it isn't installed already.
2. Go to this folder and just rename the wad+dat-files to the slots you want to use for them. For 'how-to' see my tutorial
here.
3 Last: copy and paste the tracks to the GP4-directory (wad: main GP4-directory, DAT: main GP4-directory/circuits)
Thats all!
Sadly it needs a bit time but it'll be faster than waiting for authors releasing a non-TSM-version
.