I've been tinkering with various settings after reading the manual to get the tablet to work the way I want.

What I want:
Relative-style mapping so I can work with one or two monitors easily without constraining the tablet to half its resolution, or restraining it to one monitor,
high Pressure sensivity, so just a gentle slide will make a (thin) stroke.

What I get:
using the WACOM IV setting : Absolute mapping, ok pressure sensivity.
using the WACOM II-S setting : Relative mapping, only max pressure detected (255).

In the test pane, with Wacom II-S, if I pick Pressure Mode and click Send, I get exactly the behavior I want on the scratchpad. However, the setting will not carry over to Gimp, and the clicking gets erratic (clicking at random times when hovering.)
Gimp doesn't seem to handle presure in Wacom IV setting either.

Here is my current condition:
Mac OS-X Leopard, Macbook pro (intel)
Wacom Digitizer II (UD-0608-R), serial plug with a IOGear usb-serial converter.
Gimp 2.4.6.
Main monitor: 1440x900 (laptop monitor.)
Second monitor: 1280x1024 (external monitor.)

and my current settings which most closely fit what I need (with which I only lack pressure sensivity)

Baud rate : 19200. No parity, 8 bits, 1 stop bit. No CTS, no DSR.
Command set : Wacom II-S, binary output (note: ASCII mode works, too, but the cursor won't reach the second half of my second monitor).
Line terminator: CR (probably doesn't matter)
Origin: top-left.
Coord system: Relative.
Reading height: 8mm+.
Pressure sensivity: Firm
Transfer Mode: Suppressed.
Transfer rate: Maximum.
Resolution: 1270 lpp
No tilt info (my tablet doesn't support it, I think, and I don't need it anyway.) No multi-mode, plug n play checked, no OOR data

Increment: 2
Interval: 0
Res: X 1270 Y 1270
Scale: X 10240  Y 7680

Mapping tab:
Tablet: All (10240x7680).
Screen: All (2720x1024. Note that there are two monitors : 15" widescreen and 19" 4:3)
Button mapping:
Tip : Button 1.
(others don't matter much)

So, is relative positioning and presure sensivity possible with this model?