Cellar temperature is generally anywhere between 7-18 degrees Celsius (45-65F) though people don't often go above 13C (55F), so there's a decent range to be in.
You can use your fridge. For comparison you can fill a glass with the same volume of liquid and set it next to the bottle, leaving a thermometer in it. As long as they start off near the same temperature, that'll give you a pretty close approximation of the current temperature of the beer. It might be easier to chill to the fridge temperature then let them warm back up. It's not going to damage the beer and most fridges are close to the bottom end of "cellar" anyway so it won't take too long to warm up to where you want it. Evaporation and glass thickness are going to create a difference, but given the range of temperatures, it should be close enough.
If you wanted to get really fancy, water is a much better conductor of thermal energy than air. You could get a large jug and fill it with 13C water, then put one of the Westy bottles in it for maybe 10-20 minutes, stirring frequently.
Though all that said, when trying expensive and multifaceted beers like this, I really enjoy chilling them to my fridge temperature then nursing the beer for a good while to compare the flavors as it warms up.