Four2hex was written to convert the housecode based on digits ranging from 1
to 4 into hex code and vica versa. 
Four2hex is freeware based on the GNU Public license.

To built it:
$ make four2hex

Install it to /usr/local/bin:
$ su
# make install


Here an example from "four"-based to hex:
$ four2hex 12341234
1b1b

Here an example in the other (reverse) direction:
$ four2hex -r 1b1b
12341234

Enjoy.
Peter Stark, (Peter dot stark at t-online dot de)