When a Dash-8 entered the circuit on a 5 mile final for runway 36, an amateur Vans RV-6 reported downwind for runway 27. The Dash-8 crew attempted to contact the pilot of the RV-6 but were unable establish clear communications with the pilot to determine the precise position of the RV-6 and to clarify the pilot's intentions. As a pre-cautionary measure, the Dash-8 crew elected to climb to 2,000 ft to avoid the RV-6. Witnesses on the ground reported sighting the RV-6 behind and below the Dash-8 on the extended centreline of runway 36/18 as the Dash-8 began the climb. The RV-6 was not detected visually or by TCAS. The Dash-8 was re-positioned for an approach to runway 09 when the crew had received a transmission from the RV-6 pilot which indicated that he had landed on runway 36.