Depends where it is and which CC toilet you are looking at. Does it go through the wall or into the floor? You can look up dimensions of most of the man brands on the net to check. Some are nearer than others. A popular one is the Sandringham and the dimensions are here:
http://www.armitage-shanks.co.uk/fil...gham6_ccwc.jpg
You can fit an offset pan connector into the wall outlet, or a return bend into the floor. The thing you have to watch in the case of wall outlets is that the outlet is not significantly higher than the pan outlet, and in the case of floor outlets, that the pipe is too far into the room to prevent the WC from sitting against the wall.