Can't think why you might want a manual!. All Sky digiboxes have the same functionality, they all behave in exactly the same way.
(some are a bit more sensitive than others, or slightly quicker, or more reliable, or have digital audio out, but that's about the only "user differences").
Pace used to have Sky user manuals on their website, until just recently, but these have now gone! However, if you use Google and search for "Sky digibox user manual", you can still get the HTML cached version, but with no pictures!