ToME: the Tales of Maj'Eyal

I can bind a talent to "Auto-use when available" by right-clicking on it in the talent bar. But how do I do the same for an item?

Currently, it's not possible. There were coding issues with the concept. There's an addon that might let you do it eventually, here but they don't have that function yet either. (But you might keep an eye on them for later)