The file rdskboot.asm contains the program to be inserted into the
boot sector of the emergency repair disk.  There is also a message that needs
to go in that sector -- the message is contained in setup.exe's resources,
with resource id IDS_REPAIR_BOOTCODE_MSG.

I build rdskboot.com by using the following commands:

    masm386 rdskboot,,nul,nul,,
    link_60 /tiny rdskboot,,nul,,,


I then ran bin2c.exe (in sdktools, part of standard idw) over rdskboot.com
using the following command:

    bin2c rdskboot.com 45 0 45 ..\rdskboot.c REPAIR_DISK_BOOTSECTOR

This generated rdskboot.c in setup\src, which I checked in.