According to some opinions, like those who are machmir on rov tashmishan and/or davar gush, hold that irui m'kli rishon is not enough, and actual hagala is required. </jargon> I believe these opinions are brought by both the Shulchan Aruch HaRav and the Mishna Berurah. <source needed>
Accordingly, step 4 in andrewmh20's excellent answer would be amended to:
4) Pour that [heated] water over a heated stone or iron, moving the stone around the sink and pouring over it in each location.
Alternatively, if one doesn't want to do that, one could fill the sink to the brim, and then use an immersion heater to boil that water. With that method, it may be necessary to drop a hot stone in in order to cause the boiling water to overflow and cover the edges of the sink.
As always, CYLOR.