It was a longtime ago but I think the bleed air was taken from the "P2 something" I could be wrong. You had to be careful, It was regulated somehow for safety. Man was it noisy though.
You could do the same on a B206, I remember an old AME I had on a B206 on floats and he used bleed air from the machine to either refuel or adjust the air in the floats. It was a simple connection, seems to be coming out from the front end of the engine. On a 206 anyway