Zero Clearance valve lash ?
follow the same sequence as if you were adjusting for a solid lifter...turn the adjuster until you have zero lash then add the preload on the lifter....020 preload...
http://www.hughesengines.com/Upload/productInstructions/ValveAdjust.pdf
^^^THIS^^^ is what I'd do
Set them at zero, either with engine off or running if you can
If you set them engine off, learn the thingie EOIC
which means
Wrench the engine until the EXHAUST just starts to OPEN on a given cylinder and adjust the intake valve on that cylinder
Wrench the engine until the INTAKE first opens, then is almost CLOSED and adjust the exhaust for that cylinder
Figure out how much preload / turn of adjuster you get (turns per inch of thread x rocker arm ratio, best to actually MEASURE that
Then just turn them all down by the amount you "figgure" to get the preload.
Last, if you don't know what lifters are in the engine, all the above is just guesswork.