I got Haiku nightly running in Vagrant, in order to make it easier to setup build bots and compile and test software for Haiku from different host environments.
There were quite a few little shims and tricks needed to integrate Haiku nightly with essential Vagrant features; dive into the Packer source! In the future, we can promote some of these workarounds to the Vagrant Haiku guest plugin (currently written for Haiku alpha 4), and trim off other workarounds as Haiku progresses.
For my purposes, I just wanted to see if a C project could be structured to cross-compile between different target kernels, and Haiku makes lucky number 13! I've added a Haiku amd64 demo to my tonixxx project, and may one day add Haiku x86 back, if x86 gets gcc 4.7 support, or I decide to backport my C code to C89, ha.