Questions and postings pertaining to the development of ImageMagick, feature enhancements, and ImageMagick internals. ImageMagick source code and algorithms are discussed here. Usage questions which are too arcane for the normal user list should also be posted here.
Looks like you need MagickSetColorspace(). We'll need to code it up for the next release, 5.1.0-1. Look for the image analog methods of MagickGetColorspace(), MagickSetImageColorSpace() and MagickGetImageColorSpace(). Note, in 5.1.0-1 you want to use MagickTransformImageColorspace() to transform one image colorspace to another (e.g. RGB to CMYK).