What do you think about the following idea:
A menu that can be used to quickly change focal length. Such menu could be activated by long press (1sec) of Disp key (or could be configured to work with long press of other key).
For example, 28-140mm built-in lens would have the following items:
When user chooses 50mm, the lens is set ('zoomed') to 50mm equivalent. Such menu does exist in Nikon P7000 (it's a G series from Nikon), and it's great to work with; DSLR users will be happy: quickly set 85mm for portraits, it's like using 85mm lens on DSLR or other case: you want to get F4.0 at longest focal length and you know that it's 105mm - just choose your desired focal length, then set F4.0 and take a picture.