Having a Gentoo32 chroot as a fallback on a Gentoo64 system is not unusual. Some things simply do not work on Gentoo 64 (as FlashPlayer 9) or you need a distcc server for the other (32 bit) systems.
I wrote a simple bash script that allows the X applications under chroot jail to connect to the XOrg server runing outside the jail.
You can find it here.
linux32 xchroot /mnt/gentoo32
I only tested it on Gentoo.