run cfengine with params

[Dave Stern]

We would like cfengine to run in two different formats yet use the same 
config file. Is this possible?

Specifically, I'd like an interactive script to use a different value 
for SplayTime which is defined in control in the config file.

Ideally, I'd like a command line parameter like:
cfengine -f ... -DsPlayTime=1
   for interactive   and
cfengine -f ... -Dsplaytime=60
   for cron

But if this can only be done by defining a class from the command line 
and having some class stanza that changes splaytime, that would be ok 
too (just work coding to set). If so, could someone show an example?

TIA