[happytappy]

I have filled cornies from 1/2 barrels many times. You need to connect the beer out from your sanke to the black cornie fitting. use the grey in fitting with a short piece of hose and a shut off on the end. Attach both cornie fiitings (shut off closed) to pressurized cornie (counter pressure) and tap the keg the beer is coming from. Crack the shut off on the grey cornie fitting and that will set your flow speed, too much speed is too much foam. when beer starts coming out the shut off, shut the valve and untap. You will need to prctice to get the right fill level, filling speed, etc but it gets easy.
Jim