If you can't dedicate an hour to read on how to make the JTAG port and then solder it all together, you may as well not even bother doing it. This is a very simple hack. In 30 minutes I had the port thrown together. Took longer to dump the nand than it did to build the port. A Falcon board would most likely add 10 minutes to the overall time.
First and foremost, you will NOT BE ABLE TO USE THIS BOX TO PLAY GAMES IF YOU HAVE XELL FLASHED! It is recommended that you be sure you have a good dump to flash back to the xbox if you ever want it to play normal games again. One day we may not have to juggle flashes around but at this point we do.
This is the initial build that is universal for all boxes. Match the colors, disregard the numbers.
(IMG:
http://img44.imageshack.us/img44/7332/wiringforxenondiagramre.jpg)
This picture here is for Falcon boards. This step HAS to be done for your board. Think of it as an extra key to unlock the door. You have to use a diode for these extra steps where you see the >| in the picture. Make sure you have the diodes facing the right direction.
(IMG:
http://pictures.xbox-scene.com/xbox360/free60/diagram-400.jpg)
Just solder it up using both pictures. If you have problems, you may need to add the diode that is mentioned in the first picture. I didn't need a diode. Using 10-12 inches of kynar wire per pin is sufficient and you want to try and keep the parallel cable as short as possible. If you have an old laptop like I did, you won't need the cable but you will find it wise to use the 100ohm resistors on the mentioned pins. If you do use a cable, the 100ohm resistors may cause a dumping issue. Don't be surprised if you're using an old computer and it takes forever to dump. It took me about an hour to make each dump, but the laptop I was using was an ancient Toshiba laptop with 64mb of ram and a Pentium MMX. Ancient stuff.
After this, get nandpro from the usual places and be sure that your parallel port on the computer is set to standard mode. Also install the drivers that came with nandpro. If that don't work after you tried all the steps, try a different mode. I had success with standard. I should also mention that on my very first try I had it working and was able to make two perfect identical dumps, so sometimes it may not even be necessary to change it.
Be sure to put Nandpro on the root of a drive. Use the command "nandpro lpt: -r16 'name of dump'.bin" and be sure to get two dumps. Use Winhex to compare both dumps. If both match, you're golden. If not, keep dumping till you get two that's identical. If you really don't care to have the 360 functioning like a normal 360 again, you can skip this. The 360's mainboard has to be plugged into power for this to work, but it does not have to be powered on.
To flash, use the command "nandpro lpt: -w16 'name of file'.bin" and that's all there is too it. If for some reason you STILL have a problem dumping the nand, try a different computer. Not all motherboards handle parallel ports the same. Some even have the pins reversed for some silly reason. It seems like a daunting task, but if you can use a soldering iron you can make this simple hack.
The only thing I'm not sure of is what Xell you need to flash it with. There are versions for the Falcon board. Don't worry about botching a flash or flashing the wrong file. The jtag port is meant to recover a flash if all else failed. If you can get it to be picked up by a computer, that nand can be flashed so long as it's not physically damaged.