I've managed this by using a grub boot floppy image. Our grub menu.lst contains:
title Solaris netinstall rarp root (nd) kernel /I86PC.Solaris_10-1/multiboot kernel/unix -B install_media=10.0.0.5:/install/solaris/5.10_1106_X86,install_boot=10.0.0.5:/jumpstart/install/solaris/5.10_1106_X86/boot,console=ttya,ttya-mode="9600,8,n,1,-" - install module /I86PC.Solaris_10-1/x86.miniroot Please not the use of "rarp" and "root (nd)". This way we're able to boot from a sparc based jumpstart server. Parameters "console=" and "ttya-mode=" required because our X86 system is running headless, managed over serial console line. This message posted from opensolaris.org
