Friends of mine had lined up a guide, who pulled out at the last minute. The went unguided and completed the trip in 4 days. They were a very strong group though - very fit and experienced. They had perfect weather too.
They filled the rest of the time allocated doing tours from Zermatt. No resting...
My advice would be to work on fitness, particularly skinning fitness. Well fitting boots are a must. I went on a shortish Cairngorm based tour on a whim a couple of winter's ago in my 'piste'* boots and made a mess of my feet. I could feel it happening, but needed to get back to civilisation. It negatively effected the rest of the touring that week.
You may need to do some ropework too in a couple of places. If you're confident, good, but if not, knowing what you're doing is useful, as even with a guide, an exposed windy couloir is no place to get to grips with it, especially if you're abseiling/stepping on ski. However, if you're rad, just drop in.
* Given that I'm a telemarker, the only real difference between my piste boots and the ones I use for touring is the stiffness and height of the shells. I often use the same inners. I tend to just pick the driest inners on the day.