I have been using Tellico for a few years, and recently read that it can use a CueCat as an input device. However, I cannot find any hints on getting this to work. Google searches for 'Tellico cuecat' find references to changelog entries for Tellico that say "Fixed CueCat decoder to work for UPC and ISBN values. ..." but not much more.

Anyone know how this works?

CueCats are keyboard wedge devices (or in the case of the USB one, HID), meaning they "type" the ASCII data from the barcode into whatever field you have selected. You don't need any special software or settings to handle them.

The CueCat itself has to be modified to do this however, as from the factory they used some sort of encoding that encapsulated the ASCII data into some proprietary format for the CC software. There are many guides online about how to do this, or you can simply buy one that has already been modified (as most of them are anymore).

Tellico will work with unmodified CueCats, as well as modified ones. In the Internet search dialog, change to an ISBN search, and just scan the barcode. That should ready the ISBN and start the search automatically.