[Boost-users] Cross compiling

We're using boost, and I'm tasked with getting it working on an embedded board, via BlueCat linux. The BlueCat envorinment is its own little world, meant to make it exceptionally easy to build things for the target. Because of this, they violate a few expectations for a cross-compile environment. One of these is that their compiler looks for headers in the wrong place for boost. What I am trying to figure out is how to tell the boost build process to append a path onto the list of include search paths. setting HDRS, either in the environment or on the bjam invocation line doesn't seem to help. I guess it's not propagating down? Thanks in advance for your advice.