I've 64 bit desktops which I use for development & testing. The CPUs don't have the vt support. I'm willing to use any Linux OS and any VM software to get a 64 bit guest. Is it possible?
Sure. If you run a random Linux distro on them, almost any virtualization product (everything except kvm, I think) will work. Because your host OS is 64-bit, 64-bitness in guests shouldn't be a problem.
Update: phresus has a good answer on how VMware and VirtualBox actually do not support 64-bitness in VM's unless VT is available. I now agree with phresus' post below: go with Xen, since it does not rely on VT being available.