Modulation delay is a delay whereby the original tone is unaltered, but the a little (or much) chorus or flange is added to the repeats. This is what Edge uses as he doesn't like plain and simple delay.
Unfortunately modulation delay is deader then the Dodo as far as manufacturers are concerned. It used to be everywhere on rackmounted delays in the 80's but these have also disappeared completely. As far as I know the only units that still have mod delay are the Electro Harmonix Deluxe Memory Man (analog only), the Line6 DL4 delay modeler (both digital and analog mod delay), the TC Electronic D2 rack mounted delay and the Line6 Pod XT (analog mod delay). As for what Edge uses, he mostly uses the TC Electronic 2290 Digital Delay (discontinued, costs between $1000 and $1000 on E-bay) and the Korg SDD-3000 (80's unit, even rarer)
Your options are:
- accept that you can't emulate mod delay and learn to live with it. And guess what, on most gigs you'll play you'll have such shitty sound anyway that 99% of all people won't notice. Only when you enter serious U2 tribute country will it start to matter. But then getting mod delay will be the least of your problems. To see what you would need, go see Eventide's effects rig in this thread
http://forum.interference.com/t172229.html
- Get one of the units I mention, or shop on Ebay for a cheap 80's rack delay unit. The Line6 DL4 doesn't have the best mod delay they say, but it does have 15different kinds of plus the ability to loop, making it a very versatile tool. The Pod XT is a very good all round unit, especially the Live version. Electro-Harmonix, they don't have a good rep regarding durability as they don't seem to put the stomp in the word stompbox. The TC D2 is very versatile, but rackmounted, so you'd need a midi controler as well. A good tip might be some old 80's unit. Since all the Edge wannabes go for the SDD-3000, the SDD-2000 or SDD-1000 are usually a bargain.
- Final option, mod your pedal. It is possible to modify delay pedals so they come with a send-return loop. In which you could then hook up a chorus pedal. And thus create the desired effect. Use your google fu to see what's oput there and can be done. Besides, modding is fun. Nothing I like more then opening up a pedal and fire up my soldering gun to remove and replace electronics to improve the sound. Usually using one of this guy's kits
http://www.monteallums.com/Product_links.html