Sorry for the delayed response on this one also.
You’re right, CabWriter does assume vertical grain direction on cabinet carcass sides and horizontal on the cabinet bottom and vertical on the backs. The length of the part is always in the direction of the grain. Right now, all you can do is disable Auto-Swap for that part in the Extended Entity Info box, but then it just defaults to the longest dimension being the length, which really isn’t what you want either.
In the case you’re talking about, does the grain go front to back on the sides, top and bottom of the cabinet carcass? What about the back?
To accommodate this, we would have to have a parameter that could switch the grain direction default, as you mention; we currently don’t have that. I can add it to the list for future consideration.