For an unknown reason, 9 won't install on a partition containing X. The trick: install 9 on another partition, and before restarting, copy all the 9 folders to the X partition; trash the 9 folders from the nopn-X partitions. If necessary, remove the Finder from the System Folder before emptying the Trash.
And there you go.
that reminds us that 9 is indeed a smalll-easy-moveable system compared to X!
greg