I don't think you can get anything with a Chromate finish anymore.

There are some DIY plating kits that use zinc to simulate chromate.

www.caswellplating.com

http://www.caswellplating.com/electroplating-anodizing/zinc-plating-kits.html

The layer of plating is not up to what you would get with an industrial process... but it should work.

Lots of youtube videos on it.