Calling process:

args = ['/wxdisk/PowerBridge/bin/CustomForecastGUI']
if paths:
    iter = model.get_iter(paths[0])
    args += ['-l', '"%s"' % (model.get_value(iter, 5),)]
os.spawnvp(os.P_NOWAIT,'/wxdisk/PowerBridge/bin/CustomForecastGUI',args)

Recieving process:

opts, args = getopt.getopt(sys.argv[1:], 'l:', ('location=',))
for o, a in opts:
    if o in ('-l', '--location') and a:
        self.selectLocation(a)

Example:

# script.py -l "Boston, ma"
 [('-l', 'Boston,')] ['ma']

# script.py -l Boston, ma
 [('-l', 'Boston,')] ['ma']

Expect from the first example:
 [('-l', 'Boston, ma')] []