Per,
The file you need is in the first partition of the SD card you downloaded - I believe I made an 8MB space at the front of the updater card to put U-Boot there for these kinds of rescues. You just need to
dd if=u-boot-2009.01-2.0.6-efikasb of=/dev/mmcblk0 skip=1 seek=1 bs=1024
The DIP switches depend on which SD card slot you use, for the side slot it should be all the switches set to "off" (they default to "on on on off" for NOR, "off off off on" should use the microsd slot). I may have that reversed but you'll notice when it doesn't do anything and realize you need to swap the last bit over. To get to the switches pop the keyboard - it should latch away if you use a small screwdriver or awl to push the latches at the top of the keyboard, there are 4, start from the right. There are small catches 3/4 of the way down the length, so when you try and lift it forward, be careful as too much pressure or tugging on the keyboard will bend it. A little jiggle will make this easier.
Once you've gotten to that point, without a serial board it gets a bit tricky: it won't run the autoupdate utility from the SD card because it will detect the running SD U-Boot as a current version. You will need to edit the boot.scr script provided (just edit it in a text editor, remove the garbage header, save it, mkimage it again) to set the u-boot date code to something around today's date to make sure it's going to flash.
IN THEORY, the system should flash it and then power off. You'll see the caps lock led blink 3 times then it'll shut down. At this point take the SD out... flip the DIPs back, et voila. However if the system is constantly rebooting and flashing, you have those 3 blinks to basically kill the system (yank AC with no battery) or it will be halfway through a flash update and NOR will be invalid again.
If we're at the point we're having more trouble at this point please give me a nudge and I'll create a solution for rescues that will suit your exact situation.
I am curious, how did you get to this state in the first place?