I don't use Xen, but I was under the impression that Xen support had been rolled into gentoo-sources (and probably even upstream, which means it's in vanilla-sources).
I checked 2.6.27-gentoo-r8 (32 bit), there are some paravirtualization support, maybe usable for domU, but i doubt for dom0 (actually i don't know xen-tools communicates directly with the hypervisor, proxied by the kernel, or uses kernel api for that; and if the latest is the case, i don't know it provides xen-compatible api or not).
Well in worst case i will duplicate the server to an another one and will do tests on it with gentoo-sources.
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