The OS4 partition does not need to be whit in the 2gb; but you need a old FFS partition to load the kickstart modules for OS4, and that partition most be whit in the first 2GB of disk space
Any partition which shall be bootable via the kickstart ROM IDE "scsi.device" after poweron must be located completely inside the first *four* GB of the hardddisk.
Its not necessary that the boot partition for OS4 is an old FFS partition.
When you like it and you know what you are doing, you only need to store the BootLoader and the kickstart modules somewhere inside the first 4GB, boot OS4 from there and predefine a different boot partition for OS4 in the KickLayout file. E.g. my system normally boots into OS3 on partition A, except I press the left mouse button during boot (or call a script later), then it loads OS4 and reboots from partition B immediately and after a soft reboot, from partition A again after a cold reboot.
The default OS4 install procedure installs both the kickstart and WB components onto the same partition.