So I went out to Fry's and now I have a VERY cheap soldering iron

So back to the thread, I believe we are now on step 3, since I now have a cable! It just so happens Fry's also has a
USB-2925 USB TO 2xDB9 Adapter

It contains a MOSChip MCS7720 controller. There is a link to the datasheet on the product page. You also get an extra DB9 serial port you can use for something else as an added benefit! The MCS7720 outputs at CMOS level 3.3V so it should interface nice with the tablet. You need to bypass the HIN 213 RS232 line level converter on the PCB. Don't go straight out from the 12V DB9 port or that will fry the tablet!

It just so happens the Linux 2.6.23 kernel has the driver (mos7720.ko). There is a question, however, as to whether or not the driver actually works since Google has posters reporting problems. Lets hope the driver is working well in the current kernel. . .

Now it's time to go on to step 4, actually making the connector for the tablet. Unfortunately that requires spring pin contacts like are used on the tablet's battery. I will have to order those online, so it will be a while before step 4 is posted. . .