[boost] build from cvs, what is ICU_PATH?

I'm trying to build from cvs on Linux. Here's what I get: PYTHON_ROOT=/usr PYTHON_VERSION=2.4 bjam -sTOOLS=gcc stage ****************************************************** Building Boost.Regex with Unicode/ICU support disabled. HINT: define the environment variable ICU_PATH to point to the root directy of your ICU installation if you have one. Couldn't find utypes.h in ****************************************************** locate utypes.h /usr/include/schily/utypes.h Is this what it wants? How to I use it?