I recently did this with my thief/assassin character.
I had already killed Sidgier's housecarl for the Dark Brotherhood quest months ago.
When I recently loaded my thief/assassin character with Hearthfire installed, I did not receive a letter from Sidgier - instead, I received a letter from skald of Dawnstar, saying he had a bit of land available (because I had already completed Waking Nightmare)
So I bought the land in the Pale, then headed to Falkreath. The guards at the entrance immediately pulled their weapons on me and charged me for my crimes in the hold. I paid my fine of 1000 gold, and they let me go freely.
I entered the long house, and Sidgier called me a wretched dog. i asked him if there was any work available, and he said I had to pay him tribute first, and he gave me a quest to bring him some blackbriar mead, which I did (only needed 1 bottle) and he then said "finally somebody who knows how to get things done" or something like that, and I was then able to ask him if there was any other work I could do for him, and he gave me the quest to kill the bandits he used to deal with, and after completing this I was able to buy the plot of land from him.