For a long time I used the same work around. Eventually I got tired of forgetting to hold the key at the wrong time and dying and so on due to the menu popping up.
What I did to fix this was edited the sheep shaver keycodes file to map a key other than windows to option. The keycodes file follows a format of physical key ID, key code to send when pressed, #Key description.
87 83 # KP 1
88 84 # KP 2
89 85 # KP 3
108 76 # KP Enter
37 54 # Ctrl Left
115 58 # Logo Left (-> Option)
64 55 # Alt Left (-> Command)
65 49 # Space
113 55 # Alt Right (-> Command)
116 58 # Logo Right (-> Option)
117 50 # Menu (-> International)
109 54 # Ctrl Right
100 59 # Cursor Left
104 61 # Cursor Down
102 60 # Cursor Right
90 58 # KP 0
91 120 # KP .
In this example I have copied the keycode comand (58) from the # Logo Right (-> Option) line (this is the windows key line), to the KP 0 line. The end result is that sheepshaver now recognises pressing the KeyPad 0 key as a press of the windows key, but without the pesky annoyance of the menu popping up.I have attached my keycodes file
with KP 0 mapped to windows, KP 5 mapped to f1, KP . mapped to f2 and KP + mapped to f4. I use this in conjunction to keypad movement for easy access to some skill.
Key code file avaliable at: http://s000.tinyupload.com/?file_id=60678675745213497095
Happy to upload to elsewhere if it is more appropriate.
Hope this is helpfun to somebody out there