it asks me for a channel file, then head model. Is this expected?
Yes. The source file that is generated depends on the head model selected in the folder.
This process can handle both surface and volume head models, therefore the output depends on the head model.
It would be possible to rewrite this process so that it could work with no input, getting the information from the cortex surface instead of the head model, but it wouldn't be possible to use this file for simulations.
Since this process is designed mainly for running simulations, and that it is not complicated to compute a simple head model, I prefer not changing anything.
Since I do not have recordings for this particular pt, I imported a generic 'not aligned' scalp 10-20 montage, then proceeded to calculate a mock head model, however I get a lot of warnings that channels are outside the scalp and the OpenMEEG takes for ever and does not converge.
After setting the channel file in the folder, right-click on it > MRI registration > Edit: align the electrodes on the head surface and project them on the scalp (see the tooltips of the buttons in the toolbar).
Then compute a simpler forward model to save time (3-shell sphere).