Is that the same thing as the HP 82480A?
I don't think you can download the manuals from the
http://www.hpmuseum.org/ site, but you can buy a copy of the manual collection on DVDs ($32 full set) or individual CDs ($10 each).
HP-71B Math Module (HP 82480A) . . . (CD 07)
http://www.hpmuseum.org/software/swcdp.htm
I bought Version 6.00 DVD set a few years ago. It was worth the price to me at the time. I assume that sharing copies of the manuals from media purchased there with other people is not allowed or at least frowned upon, but don't seen any obvious license agreement statements to that effect on their website or on the media.