Possibilities of r.los

Hello everybody:

I would like to know if I can use the r.los command with a Longitude-Latitude
grass4.1 Location. Has anybody used it?. If not, maybe someone has developed
something similar out there.

Does anybody know the e-mail address of Kewan Q. Khawaja (M.I.T)?. He is the one who wrote the r.los program.

Thanks in advance.

Anabel Donadios
Espelsa
Spain