the speedo healer box is less in size than a match box, so could be fitted pretty much anywhere.
I fitted mine near the rear tail light under the seat, as it was dry and easy to accses if i needed to alter the settings.
Best bet is to log on to the speedohealer web site, and look at the fitting guide. that will show you where its pluged in to the loom and then you can easly trace the wire back to the box.