My suggestion would be to install debian on the sparc 10. Download and burn the net install .iso file and go from there. I say debian because I know that they have sparc support, yea redhat does but I thought it was for RHEL (correct me if I'm wrong). Also you can download Solaris 9 & 10 from Sun.com, registration required, burn the .iso files and install Solaris on the box.
As for step by step instructions, I'm sorry but thats a little out of my league. I've never played with sparc boxes before. sorry.