I would like to install hooks in the grout behind tile.

Some of the newer 3M products will mount a hook on the tile surface without drilling a hole and hold very well. I'd try that first. Next, if needed, use a ceramic or tile bit, drill a small hole appropriate for the screw anchor, push in the anchor, put some silicone behind where the hook will go and screw in the hook. You need to be very careful in tile so you don't crack it. Another reason to use an adhesive mount.