I haven't fully run the maths, but my gut feel is that you're going to be stuck for depth of field; at a focal length of 75mm, f/16 and a subject distance of 24 inches, your depth of field is "only" 1.4 inches (according to DOFMaster). Increasing focal length or going closer will reduce the DoF further, which isn't what you want. Of course, DoF is an imprecise measurement (what is acceptable sharpness to you may not be to someone else), but 2" is looking like a bit of a stretch.

I suspect the real answer here is that she's trying to use the wrong kit. For a lot of product photography (i.e. stuff which is going to appear in catalogs, etc rather than being blown up to poster size), you don't need a large sensor - but you do need to get your lighting right. With a light tent, even a relatively cheap point-and-shoot on a tripod will let you get "good enough" product shots for many purposes - and the advantage of the small sensor in a point-and-shoot is that your depth of field is much greater.