Best access is down from Santa Barbara (elev. 1.170 m), taking Anaconda: The Upper Doubletracks (MTB #762) to the start of this singletrack (elev. 990m). Coming from Bolognano (elev. 120m), you can also bike up the forest roads (MTB #763), which is very steep at the end. You'll join Anaconda: The Upper Doubletracks (MTB #762) at elev. 1.020m, just 150 meters from its end.
The trail is steep and difficult; but there are a lot of harder trails around here, so I won't rate it as "Extremely Difficult."
See this article
for more information.
(If the trail is still forbidden and you don't like the risk to pay penalty: There should be an new mtb-line leading also from St.Barbara down to Nago, called "Naranch-Trail". It should be signed.)