Since this has no answer, I'm going to take a stab and make an educated suggestion...
I'd ask a local anodizer, of which there may be a few.
I'm no anodizing expert, as I only know what I've researched on the web, but my understanding is that the finish will first need to be stripped then re-anodized from scratch.
Because there's only the one unit to do, you may need to negotiate having a company sneak it in with a run of someone else's stuff, presuming the timing in the solutions will work out okay.
I did a quick search at metacrawler.com and came up with a bunch of firms offering HA. Maybe you could stick in California and narrow it down..
anodizing "type III" prototype information
[edit]Oh yeah, and it's just about guaranteed that the color you get is entirely unpredictable.