I did exactly what Genghis outlines above. Don't forget you will need the required night experience if you don't already have it. I broke down all my flight time on a spreadsheet and colour-coded all of the flights which contributed towards a particular requirement (cross-country, solo etc).
The real trick is to find a school which will support you doing it that way. Sadly the school I used a few years ago no longer exists.
Don't underestimate the importance of the oral exam - a number of people where I was never in got as far as the "airplane" on he check ride as they failed the oral.