Everything beyond line 2008 is uncommented. That's what I meant when I said the code was uncommented.
Yes I can give you a step by step. First, do the following:
I assume you have a method of getting the files from Windows onto your Atari disks. I use Ape for Windows which has a nice function called MIRROR that alows me to take files from Windows and put them on Atari disks.
Next the files need to be converted becuase the carriage returns are in Windows format. Using MAC/65 key in the program called CONVERT.TXT and assemble it into CONVERT.COM.
To convert the files, first rename Dup.Sys Part 1.TXT to INPUT.DOC. Put CONVERT.COM on the same disk and run it. The conversion program will create a file called OUTPUT.DOC. Rename this to DUPSYS.M65
Do this for the four remaining files. Make sure that you name the remaining files DUPSYS2.M65, DUPSYS3.M65 and DUPSYS4.M65. This is important because the first file references the others.
Also download the file called INSTALL.TXT. Key it into MAC/65 and assemble it into INSTALL.COM.
Now you're ready to modify DUP.SYS on your system.
Make sure all four DUPSYS files are on the same disk. Run MAC/65 and key in: ASM #D:DUPSYS.M65,,#D:DUPSYS.COM This will run for quite some time and create the DUPSYS.COM file.
Now run BUG65. Key in R 3000 #D:DUPSYS.COM
This will load the COM file into memory with an offset of $3000. For now, don't worry about why we're doing this.
Now key in W 4540 6B05 #D:DUPSYS.COM
When the file finishes being written, key in Q to exit BUG65.
Okay we're almost done.
Copy DUPSYS.COM and INSTALL.COM onto a standard Atari DOS boot disk. Boot from the Atari DOS disk.
Issue an L command to tell DOS you want to load a file. When it asks which file to load, key in DUPSYS.COM
Next issue an L command to load another file. When it asks which file to load, key in INSTALL.COM
INSTALL.COM will load and install the new version of DUP.SYS. It will happen in the blink of an eye.
Now issue an H command to tell DOS you want to write out new DOS files. When it asks which drive to write them to, key in 1 and press RETURN
You're done! The modified version of DUP.SYS in installed and whenever you boot from this disk you will be in the new version. To install it to other disks, simply boot from this disk and write DOS files to the new disk.
I hope this was not too hard to follow. I'll be glad to answer any follow up questions you might have.