Here are the schematics for the Deluxe and Econo Furby Zappers. The Deluxe is approximately what you saw in the picture of the converted mouse. The Econo is the minimalist version for building into a keyfob like the ones used to control car locks and alarms. You should choose an enclosure to suit your particular outlook (bowtie, VW Beetle, lemonade bottle, double bed, bowl of Petunias, who cares?). Very few of the component values are critical, and if you feel like experimenting it's easy to figure out what's important. Bear in mind that very little effort has been put into optimising the range (mine achieves about a metre with an average current of a few milliamps - I expect the battery to last almost as long as the shelf life) or performing mechanical, cost or production engineering etc - the whole thing was knocked up in spare moments over a weekend. Please don't feel obliged to send me ideas on how to improve it :-) - there's an almost infinite number of ways to achieve the same result, and I can think of lots of them, including some changes to the original circuits and software to reduce the component count further. I'm not really bothered; my unit is perfectly functional as it is, and I want to move on. Just remember that this is a presentation showing how I did it, and my thoughts on the subject - if you proceed on the basis of anything you might find here, you do so entirely at your own risk. Having said that, to the best of my knowledge, this is all good stuff. You can get the hex file you need to make the PIC work by clicking HERE (irpod.hex - 559 bytes). It should appear as text and you can then save it or copy to clipboard and save it or whatever. You'll need a device programmer - dead easy to build (lots of info online) if you can't buy or borrow one. The schematics are pretty much self-explanatory.
Please drop me an email if you have any success with this, just to satisfy my curiosity, but forgive me if I don't reply - I expect to be too busy working on the next great thing.