I am curently working on updating Gentoo/SPARC for 32bit support on sun4m. I currently have a working chroot and will be building stage3 images with catalyst and hosting them here.
Chase Rayfield - Contact irc.freenode.net #gentoo-sparc nick: cb88
Gentoo Portage does not currently provide a sparc32 profile so you must convert the sparc (aka sparc64) profile to suite. I intend to provide a script to do this at a future time. Or reintroduce sparc32 support in mainline portage. For the time being do the following. Grap a "sparchacks" snapshot from the snapshots link at the top of the page.
Build QEMU yourself or Grab a copy of qemu from here if on Windows:
QEMU Windows builds qemu.weilnetz.de
Download and isntall qemu into a directory.
Download the latest sparc32 iso from the links above.
Make sure to save it in the folder where qemu is for simplicity.
Open a commandline and change to the folder you intend to run qemu from.
You can then boot iso with ./qemu-system-sparc -cdrom install-sparc-minimal-20140620.iso -boot d
If you want to install to a disk you will need to create a disk image.