Comment 4 for bug 364916

if acpiphp.ko were collected by the -virtual kernel image, wouldn't it "just work" for you (except for loading the module)

Ie, if
a. debian/sub-flavours/virtual.list had 'drivers/pci/hotplug/*', then acpiphp.ko would make its way into the -virtual image.
b. That is the kernel image that is installed by vmbuilder, so your suggestion of loading via /etc/modules would work, and be easily enough enabled by a --execscript program in to vmbuilder.

I think that 'a' definitely needs to be done, a "virtual" kernel should support hotplug.
I dont know exactly what the best way to get the module loaded would be.