Not sure about the string either. These aren't my favorite type of hinges but the ones I have installed, I drilled a hole in the center of each slot into the control surface/wing/stab. Then I attached one of the very long/flexible applicator tips to the CA bottle. Insert the hinges and control surfaces in place then insert the flex tip down into the drilled hole and apply the CA liberally . The "hinge" will wick it in and down and attach it to the wood.
I'd rather use nylon hinges and use small straight pins to "pin" the hinges in. Once they are cut/trimmed they are hardly visible.
The hinges I like to use most often,when/where I can are the hinge points