rtcontrib and mirror systems

I found the email from may 2005 which had the man page of rtcontrib and this statement from Greg Ward:

"Rtcontrib can also be used by the more adventurous among you to
compute input/output relations for devices such as light pipes and
shading systems, although I have yet to test such an approach,
myself."

I would like to try this for an anidolic system of mirrors (set of parabolic mirrors, thus cannot be accurately modeled with direct sun), but I have not yet figured out from the man page quite how to do this.

I wonder if anyone else has attempted something similar and would be willing to tell me about it, or if Greg has experimented with it.

Thanks for any help,
Sian

p.s. If I manage this, I will also be attempting to use Daysim to do a daylight autonomy... if anyone can see any potential problems with this, please let me know.