As a person that mainly plays supports and recently tried out the new items like Shard of True Ice and Mikael's Crucible. There are times where I would rather apply the actives onto myself instead of an ally but I have noticed there is no way to self-cast an item unlike a spell. Abilities you can smart cast using alt+a spell, but there is no such thing for items. You could smart cast it or you can click on yourself, but I see on reason why there can't be a self-cast item option within key bindings.

TL;DR Currently no self-cast item option like alt+ability use.