The jumping-off point for Kompong Luong is the town of Krakor, 32km east of Pursat. From Krakor to the boat landing, where tours begin, it's 1.5km to 6km, depending on the time of year. You can get a ride on a moto for 2000r to 5000r.
Note that a boat ride to or from the Kompong Luong homestays will set you back US$5 (each way). If you book a tour, the boat will drop you off at the homestay for no additional charge.