Use a sharp peeler to remove only the colored part of the lemon zest from 2 lemons, in large strips. Try not to remove the bitter white pith, but if you do, you can use a small, sharp knife to scrape it off. In a saucepan, gently heat the cream and milk just until steaming and small bubbles form around the edge of the pan. Use the small knife to scrape the seeds out of the vanilla bean pod and add the pod, seeds, and lemon zest strips to the warm cream. Remove from the heat, cover, and let infuse for 30 minutes.
Place a medium-sized bowl inside a large bowl filled with ice water. Set aside.
In a clean saucepan, heat 1-2 inches of water over medium heat until simmering. Using a balloon whisk, in a heatproof bowl, beat together the egg yolks and sugar until smooth and very pale yellow. Reheat the cream mixture just until it begins to steam, but before it boils, and then slowly pour it in stages through a fine-mesh sieve into the yolk mixture, whisking as you add it (it's easier if you ask someone to help you with this step). Stir the mixture together thoroughly and then place the bowl on top of the saucepan of simmering water. Stir the mixture slowly until it thickens enough to coat the back of a spoon (or reaches 185F/85C). Be careful of the steam when you remove the bowl from the saucepan. Pour the ice cream base into the medium bowl (the one set in the larger bowl of ice water). Use a fine zester (a microplane works best) to zest the remaining two lemons into the base. Stir and let the base cool to room temperature. Press a sheet of plastic wrap onto the top of the base, cover, and refrigerate for at least 4 hours or preferably overnight.
When you are ready to make the ice cream, juice the 4 Meyer lemons and strain the juice through a fine-mesh sieve. Stir the juice into the ice cream base. Review the steps of setting up the ice cream maker (esp if you have a Cuisinart like I do) and then freeze the ice cream according to the manufacturer's directions (or mine). Scrape the base into an airtight container and freeze for at least 1 hour before serving.