edit: oh wait. this is where an IV calculator would be essential i suppose. safe to assume genderless scouting is only possible with IV calculators then? i've never used one (new to the scene) but i'm sure it's intuitive enough.
Pretty much. You'd need to use an IV calculator to compare the IVs of the Ditto and the offspring. I've always found Metalkid's one fairly handy.
edit: Thinking about it, once you know the IVs of the Ditto, you could plug them into the stat calculator on Metalkid's site and find out what the stats of a lvl 50 Magnemite with those IVs would be. That might be a bit more involved but you could then work out the inheritance directly from the in battle stats screen, as with Magikarps.