Hello,
I work with a Wacom Intuos 4 & Paint Tool Sai Ver 1 mostly because it's the only software that I can use mouse mode properly. I've tried researching this issue but nothing ever really works. I'm hoping that someone can tweek the driver or make some setting to accommodate this, because I'm not the only one who has looked into this. I'm sure a number of other artists would appreciate something like this as well.
Mouse Mode Enhancment
Re: Mouse Mode Enhancment
Enable: Menu-file-tablet settings-coordinate mouse mode