1. Get the required toolchain and install it.
http://www.handhelds.org/moin/moin.cgi/Linux26ToolsAndSources

2. Get the boot loader source code
http://www.sdgsystems.com/pub/ipaq/hx4700/src/bootldr-1.2.0.tar.gz

3. Mindlessly type "make", hoping it to build everything and misserably fail.

4. (Optionally) Post questions to mailing list and get absolutely no response.

5. Realize that the 3.4.1 toolchain does not come with everything. Get a complete one somewhere, install then use it from now on. (This includes changing the .bash_profile to modify the PATH) I happened to already have complete 3.4.2 toolchain for some other project.

6. Get zlib source code.
http://www.zlib.net/

7. Cross-build zlib library.
prefix=/usr/local/arm/3.4.2/ CC=/usr/local/arm/3.4.2/bin/arm-linux-gcc ./configure
make install

8. Open os_linux.mk in the bootloader source directory and modify following 2 lines.
LIBZ_INCLUDE_DIR=`which arm-linux-gcc| sed -e 's/bin\/arm-linux-gcc/include/'`
LIBZ_LIB_DIR=`/usr/bin/which arm-linux-gcc| sed -e "s/bin\/arm-linux-gcc/lib/"`

9. Then make. Few files will be created.

10. Open doit in the bootloader source directory and modify lines accessing the SD/MMC reader.

11. Execute doit to get a file named 'romfile' and (optinally) flash the binary into the SD/MMC card.

12. Now you are free to modify the source and get your own bootloader running.