I'd reccomend making a button for the script - for instructions on doing this please see the 'turning your favourite scripts into buttons' tutorial in the tutorials section.

Usage:
1) Select the objects that you want to rename and run the script.

-------- Input Description ----------------------------------

Rename Children -
Renames all the children of the selected objects.

name to prefix / suffix -
the text you want to add to the fron or back of the current name

prefix / suffix checkbox -
If checked then the text will be added to the fron of the current name, if unchecked then it'll be added to the end.

Cut from Front / End -
Dictates whether to cut characters from the start or the end of the current name.

Number of Characters -
The number of characters to cut - note that if you want to completely replace the name of the objects then set this to some high number so that all the pre-existing characters get cut.