Help cross-compiling expat

I am not all that familiar with building libs in linux - I am trying  
to build expat for a different target system than the system I am  
building this on. It appears that I am suppose to use the configure -- 
host=HOST option, but I don't really know what to put for HOST. The  
top of my toolchain is /opt/hardhat - however all of the toolchain  
bins are at "/opt/hardhat/devkit/ppc/405/bin"

I am able to compile object files successfully, by simply redefining  
the CC variable as:

COMPILER = /opt/hardhat/devkit/ppc/405/bin/ppc_405-
PPC_INCLUDES = /opt/hardhat/devkit/ppc/405/target/usr/include

CC = $(COMPILER)gcc
CXX = $(COMPILER)g++
AR = $(COMPILER)ar
LD = $(COMPILER)ld


INCLUDES = -I$(srcdir)/lib -I$(PPC_INCLUDES) -I.

.....and so on


however, the linking seems to use the libtool defined by the LIBTOOL  
env variable, and ignores the "ld" definition above.


Any help here would be appreciated...