There's a way to map a hardware button to toggle the screen rotation,

Instructions for wm6.1 users
1. run the registry editor and navigate to HKEY_LOCAL_MACHINE\System\GDI\Rotation
2. change the value of HideOrientationUI from 1 to 0
3. go to winmo settings > buttons to map it to ur button :D

Not comfortable with registry editing?
Here's an program that allows you to rotate the screen manually.
http://forum.xda-developers.com/showthread.php?p=3050329#post3050329


Insutructions for wm6.5 users
Download the following file to enable both rotation and wm6.5 settings
http://www.4shared.com/file/184670092/bf816e9d/Enable_Settings_rotation_OII_W.html

otherwise, follow the steps below,
1. run the registry editor and navigate to HKEY_LOCAL_MACHINE\System\GDI\Rotation
2. change the value of HideOrientationUI from 1 to 0
3. navigate to HKEY_LOCAL_MACHINE\Security\Shell\StartInfo\ and change the value of 'HideSettings' to '0'
4. go to winmo settings > buttons to map it to ur button :D


From the picture on the left, you can find 2 settings. The one blue/grey icon represents the Samsung setting while the grey icon (circled in red) is the winmo settings.

If the winmo settings icon is missing, go to the registry of HKEY_LOCAL_MACHINE\Security\Shell\StartInfo\ and change the value of 'HideSettings' to '0'


P.S. Samsung apps will kick the screen back to portrait mode