To install h2b simply type
make clean install
You may want to change config.mk depending on your system.
Ebuild for Gentoo users may be found in: https://github.com/arkamar/overlay/tree/master/sys-apps/h2b
Simply put your HEX input to a standard input of h2b and the conversion will be printed to the standard output.
Read man page for more information and example.
Please report them.