I'm not a specialist, but I studied the Create a bootable HFS+ partition and a FAT32 partition on one external drive hint to do this. It works for me, with a Powerbook, iPod mini 4GB, Tiger, and tested on Windows XP.
Read on to see how I created an iPod with FAT32 and bootable HFS partitions, while maintaining its ability to be used as an iPod.
Here's what I did...
Top level command (? for help): e Name of device: /dev/rdisk1 Edit /dev/rdisk1 - Command (? for help): d3 Command (? for help): c First block: 65599 Length in blocks: 6433888 Name of partition: iPod Command (? for help): p Command (? for help): C First block: 6499487 Length in blocks: 1500001 Name of partition: WIN Type of partition: DOS_FAT_32 Command (? for help): p Command (? for help): w confirm and Command (? for help): q Top level command (? for help): q
~ Hopper$ fdisk -e /dev/rdisk1
fdisk: could not open MBR file /usr/standalone/i386/boot0:
No such file or directory
The signature for this MBR is invalid.
Would you like to initialize the partition table? [y] y
fdisk:*1>edit 1
Starting Ending
#: id cyl hd sec - cyl hd sec [ start - size]
------------------------------------------------------------------------
1: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
Partition id ('0' to disable) [0 - FF]: [0] (? for help) b ou c
Do you wish to edit in CHS mode? [n] n
Partition offset [0 - 469020]: [63] 6499487
Partition size [1 - 469019]: [469019] 1500001
fdisk: 1> p
Disk: /dev/rdisk2 geometry: 992/128/63 [7999488 sectors]
Offset: 0 Signature: 0xAA55
Starting Ending
#: id cyl hd sec - cyl hd sec [ start - size]
------------------------------------------------------------------------
1: 0B 805 126 30 - 991 127 63 [ 6499487 - 1500001] Win95 FAT-32
2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
fdisk: 1> w
fdisk: 1> q
~ Hopper$ pdiskMac OS X Hints
http://hints.macworld.com/article.php?story=20050822041040570