If possible, I would just try phoning them. Electroplating can be expensive though.
I have an old Hot Rod Magazine from the 1950's in my collection that shows how to electroplate chrome pieces and in my chemistry class, we copper plated something using a penny, a solution, and a 12 volt car battery.
It worked sort of like the part was the negative cathode and the penny was the positive. The negative ions were attracted to the positive ones, which was the part, and they floated over to the part and plated it. You need a solution between the penny and part, which I forget what that is. I also forget the direction of the polarity. You'll have to experiment or look it up on the internet. (Chem class was in 1998. sorry)
You could always copper plate the entire thing and then mask off the "Yellow" sections with tape and then nickel plate the rest using nickels (currency). Nickel bonds to copper in the electrolosys process. Just look at any American coin. You'll see that it's a sandwitch of copper and finished with nickel.
My Dad once told me of how the old Packard Car Company chrome plated their steel bumpers. First they Zinc Plated the iron, then they copper plated it, followed by nickel and then chrome. That was known as "The complete chrome job".
This was an expensive process compaired to Chrysler, Ford and GM, but the old Packard bumpers still are chrome plated to this day. The reason why Packard did this is because they knew that chrome is pourous and if you look at car bumpers of the Big 3 in the 1970's where they chrome plated right on the steel bumpers, you can see that they have rusted through the chrome.
If you want to attempt nickel plating, I suggest using the Canadian Nickel because it is pure through and through. It isn't copper filled. If you can find some, use it as a source for your nickel plating.
The only draw back to plating your light saber is that eventually the plating will tarnish. Therefore you'll have to polish this piece from time to time.
One final note - Nickel is actually a yelowish silver. Chrome is blueish. A lot of old train coaches from the 1920's-1940's used nickel plating extensively. See if you can spot some pieces in the museam and note if this is a colour you're looking for or not.
