I know there is a tech tip on this somewhere, but I did mine a little differently so as to create a more positive lock in 2nd and 3rd gear. Looking at the shifter gate (this is the main body of the shifter that you see at the back of the pic behind the spring) I could see that there is a small thin piece of steel that rides against the flat area of the 1,2, and 3 shift positions. This is the piece of steel that causes you to have to push the button to shift out of park where the gate has detents built into it. But there is nothing in the 1,2,3 area to lock it in place except for the detents in the trans itself. If you look at the pic of my modified gate closely you will see that there are two small circular indentations ground into the gate just behind the large notch where the small piece of steel sits when the shifter is in second and third positions. Now when you push it up from first into second the piece of steel rides up into that semicircle helping to hold it in that gear. When you push up into third it is forced against the spring down against the semicircle, over the hump and into the next semicircle. Another push and it goes up into the large notch for OD.
It has the same effect when pulling down a gear. I can definitely feel an improvement in the way it locks into the gear now. There is no need to hit the button when going between 1,2, or 3, in either direction.
It aint a ratchet shifter, but its better.

 

Nice tip and explanation, thanks.