This may be on here some where. Very close to Alton Browns of Good Eats.

4 1/2 to 5 1/3 lb. roast.
4 talbespoons each of kosher salt and ground pepper.
2 tablespoons canola oil

Dry age roast in frig. for 3 days: Place roast on small rack place rack on cookie sheet. Cover loosely with paper towels. Leave in frig. for 3 days, changing towels daily.

After day 3 remove and coat with oil then salt and pepper. Preheat smoker to 225 deg., place in smoker until internal temp of roast hits 120 deg. (aprox. 4.5 hrs.). Turn off smoker, open smoker door then close, leave roast in smoker. Preheat home oven to 500 deg., after 20 minutes remove roast from smoker an place in oven for 10 minutes. Remove from oven and cover with foil for 15 minuts before deboning and slicing.

Well PR is pretty much covered this time of year, with a lot of "question' posts, my PR101 and Stuart infamous recipe.

Thanks for posting. Pretty much how some do it, so I'll have to give credit to Stuart for his version that's mentioned most often.

Smokin,
I am smoking a 10 lb. prime rib roast for my son's wedding feast next Saturday, want to get it to a little less than medium rare, and need to know how long to smoke a roast this large. I've tried to find your PM 101, and I can't find any of the 101's. Help?
SmokinSuzieQ from Kirkland, WA.

I think they might be on the main CookShack page.

Here's the 'draft' we haven't finalized it.
Draft Prime Rib 101

It's almost impossible to do it "only" on time. For the cost of the meat, invest in a remote probe thermometer (we talk a lot in this forum about them) and use it to a temp of 120 if you want "less" than MR.