My wife and I visited the canal lifts in August 2017, and used a rental car to drive between the four location from our base in the town of Mons (also contains a belfry if you're collecting those!). Driving is by far the easiest way to see the four lifts, though cycling would also be possible as a well-kept cycle path tracks alongside the (now rarely used) canal.
I actually quite enjoyed this sight, particularly once the concept of balance lifts had been explained! Sadly they weren't operating on the day of our visit, so we had to use our imagination.
It's also worth stopping off at Strepy-Theiu, where an enormous lift from the 1980s replaced the four WH-listed lifts. It's crazy to see how far technology has come in a century!