Create wincombo 

Windows single boot 

MKISOPTS="-r -N -L -d -D -J"
TODAY=`date '+%Y-%m-%d'`
ISOFILE="../wincombo.iso"
mkisofs $MKISOPTS               \
  -V "W98+Office2k"       \
  -A "MS Win98, Office2000 & IE6. Created on $TODAY"     \
  -o $ISOFILE                   \
  -b Boot/TECHW0RM.IMG -c Boot/boot.cat .
dir $ISOFILE

Windows multi boot 

md ~/briefcase/wincombo/isolinux

Files 

cp /usr/lib/syslinux/isolinux.bin .
cp /usr/lib/syslinux/memdisk .

isolinux.cfg 

cat <<EOF > isolinux.cfg
PROMPT 1
DISPLAY /isolinux/menu.txt
DEFAULT   2
TIMEOUT 100

EOF

ls Boot/*.img | cat -n | awk '{printf "LABEL "$1"\n  KERNEL /isolinux/memdisk\n  APPEND initrd="$2"\n\n"}'    >> !$

$ cat !$
PROMPT 1
DISPLAY /isolinux/menu.txt
DEFAULT   2
TIMEOUT 100

LABEL 1
  KERNEL /isolinux/memdisk
  APPEND initrd=Boot/TechW0rm.img

LABEL 2
  KERNEL /isolinux/memdisk
  APPEND initrd=Boot/win98se.img

  -- The 'KERNEL' has to appear under every LABEL!

ls Boot/*.img | cat -n | sed "s/$t/) /; s|Boot/|Boot |; s/\.img$//" > menu.txt

$ cat !$
     1) Boot TechW0rm
     2) Boot win98se
history 
$ ls Boot/*.img | cat -n | awk '{printf "LABEL $1\n\tAPPEND initrd=$2\n\n"}'
LABEL $1
        APPEND initrd=$2

LABEL $1
        APPEND initrd=$2

isolinux.cfg, history 1 

The problem of the following approach is that using 1 or 2 doesn't work when booted.

cat <<EOF > isolinux.cfg
PROMPT 1
TIMEOUT 100
KERNEL /isolinux/memdisk
DEFAULT   win98se

EOF

for ff in Boot/*.img; do printf "LABEL $(fname $ff)\n\tAPPEND initrd=$ff\n\n"; done >> !$

$ cat !$
PROMPT 1
TIMEOUT 100
KERNEL /isolinux/memdisk
DEFAULT   win98se

LABEL TechW0rm
        APPEND initrd=Boot/TechW0rm.img

LABEL win98se
        APPEND initrd=Boot/win98se.img

Disk image 

MKISOPTS="-r -N -L -d -D -J"
TODAY=`date '+%Y-%m-%d'`
ISOFILE="../wincombo.iso"

mkisofs $MKISOPTS -f            \
  -V "W98+Office2k"             \
  -A "MS Win98, Office2000 & IE6. Created on $TODAY"     \
  -o $ISOFILE                   \
  -b isolinux/isolinux.bin -c isolinux/boot.cat \
  -no-emul-boot -boot-load-size 4 -boot-info-table .

dir $ISOFILE
-f     Follow symbolic links when generating the filesystem.  When this
       option  is not in use, symbolic links will be entered using Rock
       Ridge if enabled, otherwise the file will be ignored.

burn test CD 

cdrecord dev=0,0,0 blank=fast
cdrecord -multi dev=0,0,0 -eject -v speed=4 ~/try/wincombo.iso