Also did mine myself. Not too hard. Mine had 16 holes per rail. I even drilled out all the holes straight threw the frame rails and used longer bolts/washers/lockwashers/nuts. I didn't like the smaller threaded holes that were in the frame rails.
If you get them, do yourself a favor and insert the bolts prior to installing the rails - this will get all of the grooves cleaned out and makes it easier to install later. Also use some anti-seize on the bolts when installing...you will appreciate this later.
There are a lot of different vendors selling them - look in the Group Buy section of this forum and check out the different styles!
Yeah, search some and you'll find some good threads regarding install. If your FJ isn't new, you will want to use a tap to clean the threads out before trying to get the bolts in. If you don't, it will be near or completely impossible to get the bolts in.
If you do have to tap, that is the most time consuming part of the install since you can't fit a tap's T handle on the tap when doing the upper holes. I used a small open-end wrench to turn the tap on the top holes. Total install time 2 hours.
You'll also see many suggest using a friend to get them on. I did it by myself buy laying the slider on the box it came in, right underneath where I would be mounting it. I used the packing bubbles to raise one end, then lifted the other end and started a bolt. After getting that bolt started, I went back to the propped-up end and put a bolt in it. No big deal to install by yourself like that.
I put mine on, got the bolts fingered in there and then discovered that you cannot turn the upper bolt at all, even with an open end wrench. Freaking impossible. I don't know how you are supposed to tighten them! I think there should be a hole on the bracket so you could get a socket in there, but mine doesn't have that. It's kind of nutso.
X2 on the jackstands! Even with a friend it's a real pain to hold it. When I installed mine I had literally zero wrenching experience and my buddy just ended up helping me run the bolts in because I didn't clean out the holes in the frame prior to the install (big freaking mistake). Just clean out the holes before install and use jackstands to hold up the slider and you should be able to install yourself in no time flat.
About a week before install I bought 16 cheap (low grade) bolts. I sprayed the holes in the frame with "Fluid Film" once a day for 3 days. Then I took a piece of fuel line hose and cut it down so it had a very tapered (pointed) end. I then wound it in each hole. (You know like your mother used to do with a facecloth to get the dirt out of your ears when you were a kid....lol.) That cleaned most of the crud out. I then dabbed some grease on each bolt and threaded them in and out a few times in each hole.
By the time I got my sliders it took two guys maybe 15 minutes to thread in the new high grade bolts with the slider. Another few minutes to switch the brake line brackets (front to rear and rear to front on each side) and voila.
The biggest pain in the butt was to loosen all the bolts and push the sliders up so the bottom of each hole(of the sliders brackets) was up against the bolt shaft. If you simply hang the slider off the bolt it will probably shift upwards rather quickly the first time you get "on them" since the holes on my TG sliders are a tad elongated to assist with installation.