You can locate your polling station on Urban Voice Cambodia! Our friends at OpenDevelopmentCambodia have shared a dataset featuring the locations of polling stations in Phnom Penh (thanks!); to find out where your polling station is located go to the Map and turn on the Polling Stations layer (below the main list of categories).
If you’re not sure which polling station you should vote at, go to the online voter list and enter your information and the site will tell you the name of your polling station. (The site will also tell you whether or not you have been registered to vote!)
More information about the elections can be found at OpenDevelopmentCambodia’s Election page.