How to compose a mixed (audio + data) CD image (ISO) from the command line

I have a set of audio files (WAV format) and a collection of data files and I want to create a mixed audio+data CD image (ISO) with (preferably only) command line tools.

I don't actually want to burn a CD, only create the ISO archive so that I can burn it later (I currently don't have access to a physical CD burner).

I have been searching around for tutorials and there is a lot of info regarding backing-up (i.e. ripping) but very little to creating images, let alone mixed audio+data images.

How can I create a mixed audio+data CD image with only command line tools?