Can these be powder-coated / anodized, or replaced, if so, does anyone know where I can source such an item?

I have only seen grey/Ti coloured ones. I believe some disassembly may be involved that can be problematic if you don't know brakes very well (unless you get a brake specialist to do the work). Reassembly with all the tolerances correct is important for your safety and peace of mind. I would talk to a brake specialist. I'm sure it's been done, just be cautious about the process. You don't want a thick coating to throw the tolerances out in an unwanted area. I think its worth emailing some of our sponsors to get them to make an enquiry for you with their suppliers.
Hopefully a member with some expertise chimes in, (I've not tried it).

mickb...

has got the fever 

Thanks KoKo, I didn't think it would straight-forward, due to the issues re dismantling/stripping/rebuild,etc with tight tolerances involved. Was hoping maybe someone out there may do these from source, as a replacement product.

Unge,
I've had the fever for years, as far as this bike goes, prob started in 2010 with my boom-tubes