It only takes a few hours from Murrisk, but it is at a very northerly latitude, so you have to be very wary of weather conditions, and you can't always climb. I wrote about my experience here.
http://homepages.paradise.net.nz/margar17/croagh.htm There are signs at the bottom warning you not to climb if it's wet etc. It was calm but overcast when I started, and it turned out to be quite an adventure coming down, when it was wet and very very windy. (I slipped on some rocks and was blown around on the ground!!)
It is very stony, and on an 'ordinary' day, nearly everybody wore shoes. Maybe on Reek Sunday it is different. I think I only saw one man without shoes, and he had two young children with him, whose clothing was quite inadequate for the conditions. (I wasn't impressed.)
I have a book that lists a longer walk said to be a ten hour pilgrim walk, starting from Ballintubber Abbey and finishing at Murrisk. If you send me your e-mail address via PM I could scan it and e-mail it to you Bob.
Margaret
By the way, this is the original thread I was thinking of Bob, from April 2009.
http://www.caminodesantiago.me/board/miscellaneous-topics/topic5597.html