You said, "The imac I have uses an IDE conection to the disk drive..."
I think you made a mistake there. Your iMac does not have an IDE connection to its "disk drive", it has a SATA connection to its disk drive (HDD), but that is not relavent to the question that you are asking, I think.
It seems that you want to remove your "optical drive" (ie, DVD drive, not your disk drive), put a caddy in there and install a 2.5" SATA drive, correct? The interface for that optical DVD drive in your iMac is IDE/ PATA, so you need a hard drive bay to connect a SATA drive to that PATA connector.
Yes, you can, relatively cheaply. I just bought one from Amazon for about $10. It is an HDE, part # N105.
At Amazon, search for "12.7mm SATA HDD Caddy to PATA". I hesitate to put a hyperlink to the product, it might change.