Tzur_H: I have it mapped to hotkeys, if you look in the command history for the name of the command, and then simply add ?+1 or ?-1 after it and map it to a hotkey that works. For example: tool.attr edge.bevel level ?+1
I don't think you can import things that are not in a 1:1 or 2:1 ratio. Just make a photoshop file and use it as something like 1024x1024 or 2048x2048 and put your alpha there.
Update -- found this guy's amazing script, fbx_properties.py "Take the output from the cmds.FBXProperties() command and convert it into useable cmds code. This will allow you to quickly set attrs that you want in the FBX export ui and get the results back in code."…