....bathroom remodel but chickened out on ours because I didn't want to demo the whole wall. As it turned out, we didn't have the room anyway due to plumbing being in the way. We returned ours to Home Depot. It didn't matter for us as the (former closet) door swung in to our bedroom anyway and the traffic pattern wasn't interrupted.
Home Depot (and I assume the other big box stores) carries in stock a cheapo kit for about $50 bucks. But I would steer clear of that kit because it feels like its made of balsa wood and the metal parts are super cheap. We haven't had any problems (knock on wood) in my neighbor's but the door doesn't get much use (single woman on suite bathroom door that probably is almost never opened/closed).
So.....
Now I just looked at Home Depots website and they carry (special order) Johnson Hardware kits that I wished we had used. These are the quality parts contractors use.
http://www.homedepot.com/h_d1/N-5yc1vZbuda/h_d2/Navigation?langId=-1&storeId=10051&catalogId=10053#/?c=1&Ns=P_Topseller_Sort|1
http://www.homedepot.com/Doors-Windows-Door-Accessories-Pocket-Door-Hardware/h_d1/N-5yc1vZbuda/R-100658081/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053I would go this route.
Home depot's website is a bit lacking in the exact specs you will need for rough opening but you can refer to the Johnson website for exact specs a rough-in:
http://www.jhusa.net/You can also compare prices (and shipping) as Johnson sells direct online. HD looks like they may discount the part a bit but you need to compare shipping policies.
I used Johnson for another project - a large three door "by-pass" door kit and I was impressed with the quality.
The kits typically don't come with doors (johnson's don't) but we used our old vintage door that matched everything else.
Home Depot's cheapo in store kits only fit 80" door heights. We ended up ordering a height extension as our doors were 84" inches high. The damn extension kit was as much as the total frame kit. $50 bucks for a little bag with two pieces of wood and two brackets (Home gouges the piss out of you for special orders in-store).
I assume you can order the exact needed heights from johnson.
Hope this helps.