I recently sourced a few of these long discontinued IcyDock MB-448AR-B units and have just added a removable hard drive bay to my Ultra and it works perfectly!
Link to IcyDock MB-448AR product info. http://www.icydock.com/product/mb448ar.html
IcyDock MB-448AR-B
The bay has a standard IDE connections to the E-mu and a floppy drive style power connector.
Here it is fitted
Here is a YouTube video of the bay in action
Link. http://www.youtube.com/watch?v=Nh34WLxu6Y0
How I did the mod
The floppy drive was removed along with its cables.
After removing the floppy I added a drive jumper across the E-mus floppy board, to fool the Emu into believing the floppy is still present.
The existing IDE ribbon was unplugged from my hard drive and easily reached the bay.
The 2.5 IDE hard drive was slotted into the removable caddy.
and the power adapter was taken care of via one of these from eBay.
15cm Molex Internal Power Y Splitter Cable IDE to Floppy
£1.69 Free P&P
eBay link. http://www.ebay.co.uk/itm/220964380555?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
Features and benefits
Now i can install/remove the drive in seconds.
Backup to a laptop.
Reorder contents.
Rename files.
Catalog the drive and printout preset lists.
Add .wav and .aiff samples straight into folders and load them back into the E-mu.
Delighted