Probably the best way to do it if you have a Squirrel SCSI is the external SCSI CD Drive route.
You can put a laptop drive internally with a Fast ATA buffered interface and IDEfix its quite acceptable. I can't find the pics of my modded ones right now, but I think there must be some pics on the a.org gallery.
The other way is to put an ide cable out of the machine to an IDE drive, such as how I did the A600 on
http://www.amiga600.net. However, if I was to do it again, I would put a socket on the side so the cable could be disconnected.
Good luck!