My organization has a trial WorkCentre 7845i and saw a sliding keyboard drawer that our users are highly interested in. We love how it neatly fits underneath the control panel and have been trying to find more information about it. We are looking for the part number so we can ask our Account Rep if it can be ordered for our upcoming lease.
From the product brochure it looks like the drawer is part of the Adaptable Availability Solution and must be ordered through a sales rep: http://www.office.xerox.com/latest/SFTCE-01.PDF. The customer expectation document also identifies that it must be installed by a CSE.