I converted my RFM to SWEP1 today, it appears to be mandatory (to some degree) to do a code update after this. I struggled with this but got it figured out, wanted to document.

Step 1 - Null modems and USB to serial adapters.
Get a USB to serial port adapter. Buy one, I used a terrible brand called GearHead. Also you need a null modem adapter. All of this stuff is 9 pin. My usb serial adpater was male, so my null modem needed to be female to female.

Step 2 - Getting garbage to work in Win 7
My stupid adapter didn't work, it had a driver error basically saying it can't start the device (viewable in device manager). Here is the deal with many of these things... the manufacturer that made the one you bought made it to be used with someone else's drivers. They didn't ask for permission, so updated drivers came out to lock out these pretenders. Thank god for this guy:

http://www.ifamilysoftware.com/news37.html

Once I followed his instructions it started working. Note that you can go into device manager and go to advanced settings for this driver and choose the com port, I recommend doing this and choosing COM1.

Step 3 - Download the drivers from planetary pinball
Go here. http://www.planetarypinball.com/mm5/Williams/tech/pin2000/software.html

Step 4 - Get a program that can actually update your pin2k.
The actual real software for pin2k only runs on computers that are, at this point, only available in your mom's garage or goodwill. Thankfully we have this hero: http://brianpeek.com/post/Pinball-2000-Software-Update-with-Windows-7-x64.

Step 5 - Setup your files.
Create a directory called C:\pin2k. Put all your update files in there.
Drop your FUpdate.exe and accompanying dlls into your C:\ directory.

Step 6 - Connect your stuff
Connect your USB to serial adapter to a null modem and connect the null modem to the serial port that is inside your coin box door to the left. I had to remove the cable inside the pinball from the mount to have appropriate room.

Step 7 - Command prompt action.
Turn on game, let it boot. You DON'T need to go into test mode or anything.
Open up a command prompt on your laptop.
Browse to C:\.
Type something like this:
C:\>Fupdate.exe -p\pin2k -fpin2000_50069_0140_ COM1
Where COM# is using the actual # of the com port your adapter is providing, and where -fpin2000_50069_0140_ matches the prefix that all your update files have. It will be smart enough to match the prefix to the update files and install all of them.

Step 8. Wait for it to be done.
Don't let your computer go into sleep mode or anything.

It took a lot of trial and error for me, so wanted to document this for myself as much as everyone else.

-ben