Question
at the end of my driveway i have granite rock that is about 25 feet across and 20 feet high at a 45 degree angle i am thinking about cutting out steps so that the rock is functional as a means to get to my back yard any suggestions on how i can do this.

Answer
I thought about this over the weekend - It is a really cool idea.  In the past, when I have had a job where there is a large, imposing object like this in a key location, we have "capped" it with wooden/trex stairs or a deck. Cutting the stairs directly into the rock would be a better, more permanant solution, but more expensive.  Usually,budget is the constraining force in most home-owner projects.

To your question: In cutting the stair treads, the rock's relative friability is of concern.  If it is "solid", and when you hit it with a hammer, it won't flake off, then you may have to use the centuries old method - chisel & hammer, or hire a mason to do it for you, and he will probably use a pneumatic hammer.  If, on the other hand it comes apart more easily, you may elect attempt to do it yourself.  Be prepared for a messy operation, if you want a staircase that doesn't look too rustic, and is functional.

Layout is key.  You'd hate to put all this work into creating a staircase, to find that the tread & riser to ratio is off. Here is a website to help you determine this:

http://www.bestdecksite.com/introStairsPg2.htm

There are plent of other good sites that can help with the other  design issues (total length, widths of the stairs and landings, turns, railings, etc.).  Just google "outdoor stairs design".

You may also consider that since it is a PERMANANT staircase & not wood, once you've committed to it, there is no turning back.  Intermediate landings, turns, handrails must all be considered. Some sort of plan is in order, and you don't just want to "wing it"

Aesthetically, a straight shot right up the face may seem the easiest, but it will also be the most obvious and visually dominant.  You won抰 be able to "soften" it with plants or colors.  Consider a gentle "sweep", or intermediate landings that change direction to follow the contours of this large outcrop.

Here are some images - Not all carved directly out of a single rock, but beautiful, none the less:

http://jonathangreenwald.com/pblog/index.php?showimage=394
http://www.wuerfels.com/wp-content/uploads/57-stone-stairs.jpg
http://www.hardscapebuilders.com/Images/stonestairs.jpg
http://images.travelpod.com/users/thomasgillam/4.1257849255.stairs-carved-from-s...

And notice that none are a "straight" line to the top"

Hope it helps - best of luck.