The new LaserWriter drivers (6.0.1 and later) are better at handling longer
print jobs. If you are using older drivers, upgrade to the 6.0.1 versions
as a first step.
The PostScript "program" you refer to is not an off-the-shelf commercial
product. It's a PostScript code sequence that changes the default value of
the timeout clock. We recommend looking at the PostScript Language
Reference manual, published by Addison-Wesley. This book explains using
PostScript commands to alter the timeout.
We recommend against sending PostScript commands to the LaserWriter, as it
is quite possible to change the LaserWriter's parameters in such a way as
to make the LaserWriter permanently inaccessible.
For more information, search on "Addison-Wesley".