I highly doubt it, at least not without a lot of effort. Both the kernel and the applications it runs must be compiled for 64-bits to have a true 64-bit distro. While it's possible to also run 32-bit binaries under a 64-bit kernel (on x86_64 chips at least), they require the presence of a separate 32-bit support layer and libraries and such. This is useful for running the occasional program that doesn't have a 64-bit version, but it's no way to run an entire OS. You're much better off simply reinstalling the whole thing from scratch.
Last edited by David the H.; 02-28-2009 at 10:53 AM.