Installer searches to find packages that can be updated, then gives option to customize the selection. At this point if you try to select that option it crashes with Sig11. This means that you have to install everything it gives you, without the option to skip updating things you want to preserve.. DHCP, for example.. ;^}
Have you tried the errata ramdisk image?
This should be solved by downloading the new ramdisk image available at http://www.redhat.com/support/docs/rhl/alpha/rh52-errata-alpha.html. Create this disk according the the user's guide. If this does not solve the problem for you, please reopen the bug.