This describes how to port Yhc to a new architecture. It does not describe building which is covered in building Yhc, and should probably be read before this.
The target system must have an ANSI compliant (ish) C compiler (i.e. GCC) that can produce binaries for that platform. Whether you can cross compile C, or native compile C is not an issue.
Compile the runtime system, this is written in ANSI C. You will need a config.h file, which can either be generated from configure, or written by hand. If you need to make further changes to the source code, please send patches or bug reports. The standard build method is using a Makefile, although manually compiling and linking every *.c file also works fine.
Once yhi is running, you can use the cross platform version of yhc, as a .hbc file, and you have a haskell compiler on your target system. Of course, on an embeded system it is unlikely that you will want the haskell compiler as well.