Then: Email the office the details. For a nominal sum (like $5 - not a bankbreaker, but enough that they won't just throw away their guesses), they can participate in your Oscar pool. The person who guesses the most Oscar winners correctly gets the money collected.
You can go whole hog and get everybody to guess all the categories, but do NOT limit it to the ten major categories. Those'll be predicted in every news organ around the world the Friday before, and so you'll have the pot split by several coworkers who waited til the end to submit their guesses. The more minor categories are often where the pool is won. (Indeed, each time I've run the office pool it was Best Costume Design or even Best Makeup that put the winner over.)
In the email out to everyone copy the nominees into the body of the message. (I found the list seen in the images below here, just copied and pasted into a Word doc.) Ideally, it'll look like this.
When people return their picks to you, they need only delete the nominees they don't believe will win. Their list, in an ideal world, will look like this:
And if a list is in the body of an email back to you you can just print it out, on a single page even.
So give people until the close of business the Friday before the Oscars (Friday, February 28) to submit their lists and their money to you.
Watching the Oscars with these lists on your lap, checking off every correct answer on each list, will be an absolute blast. I guarantee this. You're likely to be more excited by the competition between your coworkers than anything happening on screen.
On Monday, the participant with the most correct guesses gets the pot. If multiple participants tie with the most correct guesses, split the pot evenly among them. You might also considering awarding a small sum ($7, say) to a participant who submits the sole correct guess for a major category. (Years ago, Amy didn't think Crash would win Best Picture, since Brokeback Mountain was widely believed to be a shoo-in for it, but in her heart couldn't not vote for it - she was the only one who voted for it, and was rewarded for her faith with a small prize [the aforementioned $7]).
Monday morning, either before or after you dole out the prizes, send an email to the participants (NOT the entire office - non-participants probably don't care, after all) announcing the winners, and list off the participants and their number of correct guesses.
In the end it'll be a fun diversion for the office, and an Oscar-improver for you. If you think of something I didn't suggest above to make it work better for you, then by all means do it (and leave a comment here telling us what you did). From this point on, how things go in your Oscar pool is entirely up to you. Your word is final.