Scroll down midway and theres a good photo of how the spring should look. Its a Tanaka airsoft model but the trigger and the bolt stop spring are identically placed so its the same set-up.
The long side of the spring faces forward, the short doglegged end goes into the slot where the trigger slides into.
Best way to do it is to place a drift pin/punch of same diameter through the bolt stop metal and the bolt stop spring, then insert the pin from the opposite side.
Or place the drift pin/punch through the opposite side and put the pin through the bolt stop metal and action.
Either way you can end up with the same results. BE careful when inserting the pin and make sure the spring is not bent or destroyed in the process. The safety may present a problem with installing the pin from that side just watch out and be careful.