If you can at least crawl on your belly to get to the location were you want to place the lights it would help to poke a hole from the attic down to mark your spot. The exact location of the lights will be determined by the ceiling joists. You will have to pick a "joist bay" closest to your desired location and center the light between the joists.
You can get a bore/drill bit from the home center (home depot) to match your desired can light size to drill back up from below based on your mark. They are a little pricey at 20 something bucks but it might make life a bit easier.
Since the lights will be located in an attic you will most likely need cans that are designated for "insulation contact" a.k.a "IC rated". You may also want the air tite cans that have the extra gaskets and air tite housings. This is assuming an un-conditioned crawl space above. One of the bigger mistakes I made in my own home was not using IC cans. I have fiberglass batt insulation but I would love to pump in a thick bed of cellulose to my crawl space but now I can't.
I just used HALO lights from Homer Depot for my neighbor's place (see below). The lights are relatively expensive (6? bucks for non-IC) but then they gouge you for the baffles (7 to 25 bucks). Don't skimp on the lights - stick with a brand name like Halo or Juno. Avoid Homer's house brand, Commercial electric. Halo has a nifty system for making the connection to the light. All you do is strip the wire about 3/4 inches and push it in to the color coded receptacle. No twisting and fiddling over head.
These were for my neighbor's place. We had to demo the ceiling as there was no space above. We used new construction non-IC units placed from below: