Thank you both!

We should get the TikZ devs to accept patches already. does anyone know
anyone who has CVS access?

Apart from Aditya’s hack, I’d also like to see Joseph Wright’s
hack<http://tex.stackexchange.com/questions/27952/cmyk-context-colors-in-tikz/27955#27955>for
ConTeXt’s CMYK colors in TikZ. Maybe we should create a module from
user-created TikZ hacks that make it work better with ConTeXt, and link to
it on ConTeXtgarden?

PS: Aditya, does your module provide everything you’d expect? like
\tikzstyle, \usetikzlibrary[something], \tikz\node{};, …? I don’t exactly
know the inner workings of plain TeX…

philipp