Hello mate, fitting them is pretty easy.
You slip under car, detach your exhaust to have room for working.. remove heat shield (easy twisty clips) then you'll have in front of you your lower side of gearshift lever and the shifter bar going to the gearbox.
Remove the 13mm nut and slip out the shifter bar.
At this point you have the bushings in front of you. Remove actual bushings (I used a very sharp flathead screwdriver then some pliers). And then you can press fit the new ones using a m8 bolt with nut and 2 large washerd in this order:
Blot, washer, bushing, lever, bushing, washer , nut.
Carefully turn the nut keeping the bolt still. Especially at beginning take a look on bushings so that they enter the lever straight. Once properly sat down.. tighten the nut/ bolt until fully seated. Then remove bolt and refit all the parts you removed! Very easy!