Buttons on neutral units

This is really simple actually, i need to have buttons that shows when a specific unit is selected.
Partly just for using the tooltip, but also for i.e. accepting quests and such.
I know how to fix the dummyspell and all, usng auras for unclickables and linking stuff with triggers, but not how to make it show to any player that selects the unit.
I would be most thankful for quick advice on this.

You mean like a button on the side of the screen (hero button)?

I don't understand the question, at all. :(

I believe he's referring to an icon in the command tray (where you would normally see the 'move' 'hold position' etc. icons).

Exactly.
What i need to know is basically how to put any kind of spell to be displayed in the tray for anyone who clicks that specific unit, and preferably how you can decide in which frame it should be placed.

Either give it unit control to that player, or make it a shop.