I am using a modification of the list_mc_hbonds.py script from Robert L.
The code relies on the find_pairs command
http://www.pymolwiki.org/index.php/Find_pairs to detects hydrogen bonds.
The find_pairs function seems to do exactly what I want. Using the
parameters cutoff=3.5, and angle=40. The results are virtually the same
than the results provided by What-If. But, what exactly means the angle
parameter? I guess is something like a cut-off compared to some ideal
hydrogen bond angle... maybe the angle defined by the
aceptor-donor-hydrogen atoms... but I am just guessing.