It's very similar in concept.
There's two main differences:
1. Imager images aren't always 4 channels (RGBA), but can be 1 (grey), 2 (grey+alpha), 3 (RGB) or 4 channels (RGBA), and the matrix needs to be adjusted for that.
2. The convert() matrixes use a 0.0 to 1.0 sample model instead of a 0 to 255 sample model.
It should be possible to convert any matrix used for flash colormatrix to a matrix for Imager's convert().