I will attach a patch that allows me to compile a compiler on Solaris 10/x86 that has a native bits size of 64 for produced code.  I created the configuration analogous to the sparcv9-sun-solaris2.* case.

With this patch I have successfully built a fully 64-bits environment (toolchain, userland) that appears to work fine.  Essentially the profile just switches the default code generation from m32 to m64, so no real rocket science in here ;)