I've never actually used it, but CogSwap just signals the motor shutdown, allowing you to then use the old knife trick to swap disks. To go about installing this, I would create an exploit disk that can be run from inside the current HDLoader (google Independence Exploit Compiler, version 5 I think). Make sure you add a BOOT.elf, probably uLaunchElf or MyPS2, then add the HDLoader.elf, CGSLoader.elf (or w/e) + all your other files. Install it to your Hard Drive from HDLoader, then run it in HDLoader to get your new set of files onto the memcard.
WARNING!!! I HAVE NEVER DONE THIS, HOWEVER< IT IS ADVERTISED AS A METHOD IN THE INDEPENDECE COMPILER, BUT I AM NOT RESPONSIBLE FOR LOSS OF FUNCTIONALITY

. It should work fine though, and I would suggest getting an FTP elf for your PS2 so you can perform easy transfers. Furthermore, CGSLoader may cause your laser to die earlier, so it should only be used if necessary, or so I hear. Check out
www.ps2hd.com for more information.