LogTicks is really nice. However, if you might wish to avoid another package or have more control over the final output, here is a template. As mentioned in a comment above, I actually hope that ScalingFunctions will be fully implemented in the future.
function[a_, b_] := Log[10, a + b]
Plot3D[Log[10, function[#^10 &@a, #^10 &@b]], {a, Log10@1,
Log10@100000}, {b, Log10@1, Log10@100000},
Ticks -> {Table[{y, ToString[Round[10^y, 0.001]]}, {y, Log[10, 1],
Log[10, 100000]}],
Table[{y,
ToString[
Round[10^y, 0.001] // ScientificForm // TraditionalForm]}, {y,
Log[10, 0.001], Log[10, 100000]}], Automatic}]

LogTicks(from the LevelScheme package) to rescale the axes. This worked for me – Sosi Mar 13 at 14:53