i heard you have to have it bright nickle plated first but how would you do a stem , or a seatclamp

It is exactly like chrome.

1 Polish to a mirror, 2 copper plate, 3 double nickel plate, 4 and then gold instead of chrome.

If _you_ actually want to gold plate a stem or a seatclamp at home it's a fairly big step to take if you are completely new to electro plating stuff.

It's probably best to start off with a home built annodising setup set up.

http://www.finishing.com/451/72.shtml

Before you start getting into the nastier area of steel plating aluminium alloy's in order to get the Gold to stick.

Personally Ted , I like 3 coats of Nickel to play it safe , before the sealing it all over with the final plate coat. :>

JB