…
You may also apply my suggestions given here…
Additionally - it is NOT obligatory for a script to appear at your menus! Only scripts with certain block, usually - in the header, appear in respective menus. It looks like this:
#!BPY
#"""
#Name: 'Cutting tool 1.1.0'
#Blender: 246
#Group: 'Mesh'
#Tooltip: 'A tool to cut a mesh by a plane'
#"""
# Script information:
__author__ = 'Emil Lozanov'
__version__ = '1.1.0 of 02.JAN.2010'
__email__ = ["Emil Lozanov, [email protected]"]
__bpydoc__ = """\
For cutting a mesh, you need to (1) select it, then (2) select
the cutter (another mesh). The cutting is done by use of the first
plane of the cutter. In case there is the cutter has no face - its first
3 verts are used to determine the cutting plane.
In any other possible situations, the script issues appropriate error message.
"""
The above is projected to add the script in Mesh sub-menu.
Regards,
Suggestion: do not go into the sea with 2.49 (besides it needs Python 2.6 I think).
Blender 2.53 will be much better and works already now rather good (especially if you are a beginner)
Blender 2.49 should to my opinion only used if you want to use a script (big one, like building a whole city…) which is not yet available (translated to) in 2.53 
…
Scripts working in Bl 2.49 probably don’t work in Bl 2.53.
Paste the code hier then I will try to understand and make it work in (latest = today version Win 32) Bl 2.53
use code (<— begin) (end —>) /code both enclosed by squarebrackets [ and ] ! inbetween your code and what you want to accomplish