Grasshopper, I know you've asked this before in a different thread, and I'm a little shocked that Tom would write that in response as he is wrong.  Tom was also the person that wrote that erroneous info in the old dreamcast faq.  And I know you so much want this to work but it simply won't.  Since it was a long time ago, I think Tom forgot why he dropped this idea.
Back in the day, we had the same hopes...mostly because SoulCalibur did indeed support the keyboard as a joystick controller (but only as player 1).  Every other game I've tried does not work like this.  In fact, I have a Dreamcast keyboard, and just tried several games right now (PowerStone, Project Justice..) and both did not even recognize the keyboard.  Soul Calibur (as I just confirmed again) does recognize it...the enter key is mapped to the start button, the arrow keys to the digital pad, and by mashing around on the keyboard I found the other 4 ABXY buttons.
But let me make this perfectly clear, SoulCalibur is the only game I have ever seen which will allow the keyboard for use as a joystick.  If this is enough for you (to play one game) then go for it.  Maybe the 2nd player will work if you plug in a second keyboard into port 2 (I doubt it though).