Locking Gas Cap Install

I bought a locking gas cap for my 2002 Buick Century and I am wondering how do you get the tether lanyard around the new cap? I got the old one off without much problem, but how do you get the ring to slip on into the new channel? Do you need a special tool?
Any help would be appreciated.

It probably won't fit. I have a locking cap and there is no channel for the lanyard. Thow your lanyard in the trash please.

It probably won't fit. I have a locking cap and there is no channel for the lanyard. Thow your lanyard in the trash please.

There is a channel. It is the AC Delco part, not the Stant locking cap, so there is a channel buildt in.....it is just frustrating that they make it so hard to get the old one in.