parameters for GTX260

I have GTX260...
can anybody tell the best parameter values for this GPU? im interested in those:
--ms --threads --lookup --blocks
and another question:
what for is the parameter --lookup and what is the proper syntax for command parameter -l / --lookup
because program wont run with parameter -l 768
can anybody tell the best parameter values for this GPU? im interested in those:
--ms --threads --lookup --blocks
and another question:
what for is the parameter --lookup and what is the proper syntax for command parameter -l / --lookup
because program wont run with parameter -l 768