Hiya, I have done this to 2 LX seats in 2 days, and its really easy.
All you need is a 12.5inche tube, screwdriver, drill and drill bit, and pliers, tape, and a sharp knife.
First, take the seat off the seatpost, it makes it easier to move and do stuff to the seat.
2nd remove the screws off the front handle and rear bumper. Take the bumper and handle off and set them aside.
3rd, I would suggest putting the screws loosely on again, so the the bolts of the seat stiffner and the bolts from your bumper and handle don’t fall out when your moving the seat around.
4th, Take a flat head screwdriver, and you should see, on the inside of your seat, along the edges, metal clips. Those are what hold the cover in place. So, just use the screwdriver to get underneath them, and ply them open a little bit, do it to each and every one.
5th, now you can remove the cover. Just peel it back and off, you should have the black cover, a thin soft foam inner that is in the cover, and a thick piece of foam. If the thin soft foam is on the thick hard foam, take it off the saddle foam, and put it back in the saddle cover. Now, set the cover aside, and throw or put the thick piece of foam away.
6th, now you should have a naked LX seat, beautiful isn’t it? now its time to drill it up! Using the drill bit and drill, flip the seat over, so your looking at the bottom of it, in the back of the seat you should see a thick section of plastic, that is just a straight ridge, and will go almost to the very back of the seat, drill the whole right at the end of it. After the drill, smooth out the edges and make sure the tube valve of the tire fits in it.
7th, now flip your base over again, you should be looking at the top of it. Slightly inflate your 12.5" tube, and run the valve into the whole you just drilled. You should now have the tube in and just flopping around. Fold the tube under so you have a straight part of the tube covering the back of the seat, and the other parts of the tube going down the middle of the saddle. You can use tape to hold it in place. Now, seeing how you have the tube on the back and middle, fold it over in the front, so it fits well in the front of your seat. Mess around with it until it fits best and will be most comfy, try not to have edges poking out, or the tube hanging off the side of the seatbase.
8th, Now you have your tube in place with tape, lets get the cover back on! Starting with the back, slowly move the cover over the innertube, pull the tape off before or after you get the cover on. Now clamp the back of the cover back with the metal clamps, put them on tight, but not too tight, you don’t want them to cut through the cover.
9th, repeat step 8, just slowly attach the cover, moving from the back, to the front, and removing the tape, so the tube doesn’t lose its position, and clamp the cover all back.
10th, take your front bumper and put it back on, its easy, tighten the screws up good. Now, on your back bumper, you should notice it wont fit because of the tube vevle is in the way. Just use a knife or something sharp and cut out the seat so it will fit around the valve. Now you got your back bumper on!
11th, make sure everything is on nice and tight, nothing is loose, and everything is just how you want. Now just put the seat back on the seat post.
Congratulations! you just made an air seat!!!
Fill up the tube to a pressure that suits you best, not to high or you can ruin the cover, not too soft or your gonna push all the way down to the seat base. Mess around and you’ll find your right setting.