Howto run greater-pre-processing:

Required:
	Python 1.5.2 or higher

As a first step you have to copy greater-pre-processing.py somewhere
into you PATH or extend the PATH to where you have installed
the greater-pre-processing package:

  cp greater-pre-processing.py /some/where/in/your/search/path

  OR

  export PATH=$PATH:/some/where/greater-pre-processing

Next, set this environment variable that points to where you have
installed the greater-pre-processing package:

  export GREATER_PRE_PROC=/some/where/greater-pre-processing

You then are able to execute

  greater-pre-processing.py

in a directory with the pre-defined files for your catchment
(you will be given further info on how to use the program).