How to fill Californian version of Worthington horizontal cylinders
 

Hi,
I'm hoping someone here could help me. I bought two 10lb alum.
horizontal cylinders from WestMarine not knowing that they would be
what someone explained to me as a Californian version, with two
valves, the central valve only one way and the second (bigger) valve
for filling. As I am out of the US I have very difficult time filling
those.
Apparently I could either replace the central one way valve by the
"normal" two way valve, which I could easily fill everywhere or I
could get male part for the filling valve. Any experience with these
cylinders? Probably getting the fitting for the filling valve would be
much easier as I wouldn't have to mess with the main valve. But can I
easily fill through the filling valve without other equipment?
I was trying to locate the fitting for the filling valve, but can't
find it anywhere. Any suggestions?
Many thanks