Hummm good question! But do you really want to go under the rain to play ghostbusters ? I will wait the sunny day 
At the time I bought my pads I didnt realize they sold the ones that looked movie accurate online and I got the regular volleyball pads at Sports Authority. I just used rit dye and did it the same way that bctsnowdevil is describing and mine came out dyed pretty well I thought. Here’s a picture of them drying, althought when they were done they looked lighter, a little too light actually.
If you didet tell anyone, no one would notes the diferense
Well as Dr Hobbs (UKGB) said above we had no luck this end on the dye front so ended up going for the paint option.
Just a Quick Recap,
First a nice few thin layers of primer on the whole thing till it’s all a nice even grey.
Then mask off everything but the pad and the small square on the inner arm bit, then sprayed the square black, and put 2 lines of black over the indents on the pads, let dry and another coat on the inner square till it’s a nice black.
Then a layer of darker grey over the pad, not too heavy as you want the hint of the pad stipes to show thru.
And Viola 
Mine at the front and ones just finished for a mate at the back Plus a nice layout of Kit shot :lol:
I hope that helps others who like me and my friends who could only find dye’s that did diddly squat for us.
ATB
TK Lee
So you just start the wash cycle and add dye? Doesn’t that… well… coat the inside of the washing machine?
Do you have a picture of your suit after the dye job?
And what color dye did you use for the suit? Black? Grey?
Russ
:lol: That’s why I do my dyeing at the laundry mat. :lol:
DOH! :lol:
I can hear it now… “This was supposed to be a load of WHITE clothes! What the hell…?”
Russ
So how should I go about dying…My green belt white.
(What were you thinking)
That’s going to be tough. You really don’t want to use bleach, as that can do bad things to fabric. Especially if used in a concentrated form. I know of one person who turned a new pair of BDUs into fabric goo when the bleach dissolved the fabric. 
Used sparingly it might lighten the green but I don’t know if you can go from OD to white. It’s always easier to go from a light color to a dark color, rather than a dark color to a light one.
Russ
I see. so what color showld I get
Actually, the RIT dye company makes an item called something like Dye-Out. I saw it in the display at the craft store today. It claims to mainly be used for removing stains such as tomato juice or ketchup from white clothes, but it can also be used for lightening the color of dark clothes.
It’s only $2, so it might be something you can try.
If you don’t want to try that… get a white belt. They’re out there.
I’ll post a link if I find a source for them. Or someone else could share their source.
Russ
That would bee graatee