Hi
I succeeded using partition- and bootmagic 7.0 .
I first installed win xp pro and partition magic on the first partiton .then I made a new primary partition using partition magic( on the same disk as xp was on).
First I did a reboot, so that partition magic could finish it's scripts. I ignored all drivemapper messages.
Then I made the new partition the active one and hide the xp partition.
After that the system tries to start from the new partiton. if you use a bootalbe install cd you can install win98 on the new partition. XP is unreachable during this phase. After installing win 98, install boot-magic. Now you can choose wich OS you want to boot. Both XP and win 98 are visible to bootmagic I did not notice any interference from the other OS. If you have a bootmagic bootdisk and installed XP on a FAT32 partition you can choose on wich OS you install bootmagic. If you use a NTFS partition you can't, you can only install it on the win 98 partition. If you used fat32 you can choose, using a bootmagic bootdisk or a win98 bootdisk. with the win98 bootdisk you can make partitions active using fdisk.exe
Partiton magic and bootmagic are easy to find (try fosi)