Well I somehow managed to get pressure working in Maya. I changed the identifier from "stylus" to "wacom" and it now works. Here is an excerpt from my XF86Config file:
Section "InputDevice"
Identifier "wacom"
Driver "wacom"
Option "Type" "stylus"
Option "Device" "/dev/ttyS1"
Option "Mode" "Absolute"
Option "Tilt" "On"
Option "Threshold" "10"
EndSection
Section "InputDevice"
Identifier "eraser"
Driver "wacom"
Option "Type" "eraser"
Option "Device" "/dev/ttyS1"
EndSection
[.....]
Section "ServerLayout"
Identifier "layout1"
Screen "screen1"
InputDevice "Mouse1" "CorePointer"
InputDevice "wacom" "AlwaysCore"
InputDevice "eraser" "AlwaysCore"
InputDevice "Keyboard1" "CoreKeyboard"
EndSection
Now it works in Maya, however, the pressure sensitivity seems very buggy. 70% of the time when I start off pressing with a low pressure it just reports 100% pressure. This makes the sensitivity pretty useless. My tablet works perfectly in Shake, GIMP and Photoshop in WINE though... so it isn't my tablet.
Well at least one problem is solved. Let me know your results and if you have this same buggy behavior.