UPDATE: Hacks no longer needed, latest Visor/SIMBL is 64-bit Snow Leopard happy! This is a similar process that I had to go through back in the day when I had to hack visor terminal in Leopard. Basically the steps are pretty easy. First you just install SIMBL and the Visor.bundle as a SIMBL plugin in ~/Library/Application Support/SIMBL/Plugins/Visor.bundle. Once that is done here is the process to get this working in Snow Leopard.