1) use a very small amount elmers WHITE glue to attach the key to the security bolt and let it dry. this is now one piece and cant fall off.
2) lay the gun down (security system facing up) on a microfiber cloth on a slippery surface like a baking sheet.
3) insert the spring and bearing, use the bolt/key to push down the bearing and turn the PISTOL in any direction needed to engage the bolt.
4) once the bolt is engaged you can just pull the key from the bolt and use a toothpick to remove the glue residue.
might work, lemme know....