Umm .. if you don't want to bother with that process, simply photograph it with your digital camera .. saves scanning a few times, stitching and adjusting contrasts, colours etc. I usually lay it on the floor and use a tripod for the camera facing downwards.. the further away you can get the less distortion there will be (stairwell?)
Errr .. the link says A5 is large .. in fact it is small .. A5 = A4 divided in half, A4 being the 'normal' size used eg for writing letters/reports .. bit less than foolscap. I'd think they mean to say A2....
Some of the newer photocopiers have a scan to net/disk function. You might find a large one somewhere that are willing to do a larger scan than you can do at home. Possibly at a public library?