I am unable to get on wifi at the moment but if you go to http://www.pokecheck.org/ you can upload the pkm file I put up and send it to your game via GTS.
When your are done editing the sav open up desmume and click on file then click on where it says import backup memory. If you have anymore questions just PM me.
....not sure if your joking or not but Ferrothorn is a 5th Gen pokemon... So the egg obtained part would be day care couple and hatched would need to be a anywhere in B/W.
Here is the code.
Activation button is select. Will be first pokemon in your party so make sure its nothing you want to keep.
If it does not work then I can post the pkm file if you would like.
lol that's what Ive been doing. Its just the constant clicking of the A button over and over again till it evolves. Sometimes 4 times depending on how many abilities it has.