Well, he uses something called a talkbox. Basically it runs the sound from your guitar into an amplifier, out a speaker, and into a tube where you can manipulate it by changing the shape of you mouth and depth of you throat. They run about a hundred dollars but you can build one for less.
These sites help me link1link2link 3
Step 1: Supplies
1 Horn Driver Here is the one I got (I might change it out for a better one soon)
* The impedance of the speaker needs to be the same as the one in your amp. I used these links to figure out what I needed.
My Amps Manual
1- practice amp (mine is a Marshal MG10 I got with my first guitar. Don't do this to your best rig.)
1- piece of 1" flex PVC pipe
3- hose clamp (got it in the plumbing department it had 1/2" threads and fits the 3/8" hose)
1- 1 PVC Coupling
1- PVC Reducer 1"x 1/2"
1- 1/2" PVC Female Adapter 1/2
1- some length of 3/8" black vinyl tubing
1 - piece of 4" wide PVC
2- 4" PVC Caps
1- 2PDT switch (I wanted a stomp switch. You could use 2 spdt switched for cheap)
3- adjustable metal bands (one small and 2 big)
1- liquid silicone (optional)
1- flat black spray paint (optional)
1- pocket full of dreams *A MUST*
Step 2: Tools
you will need-
a soldering iron
a chisel (maybe)
saw (hack saw worked fine)
helping hands (optional)
Step 3: Adding the Switch
Ok, so inside the amp you have the preamp and two wires going to the speaker. I cut those lines and put a switch on the top of my amp. One set went to the speaker and the other to the horn driver.
Remember to tin the leads on both the wires and the switch before soldering. Pull all four wired through the hole in the preamp assembly. You can use the same wires that were there for the speaker and make the wire for the horn driver 2 feet (you'll see why later).
Step 4: Pod Paining(optional)
I then drilled a 1/2" hole for the hose to exit in the top end cap. The inner diameter of the hose is 3/8" but the out diameter is approx. 1/2".
I painted mine flat black :]
give 24 hour to dry or you'll be sorry
Step 5: Pod Mounting
Step 6: Final Assembly
YOU ARE DONE!!
Soft plastic absorbs and changes the sound of your guitar. The shorter length of hose you use the better. I recently cut 4 feet off of mine and it sounds a lot fuller and less nasally.