Originally Posted by Pleiades

You only need to draw off about 250ml of coolant through the rad cap to get the top hose clear. Remove left hand grey tank cover to expose the hose (there's plenty of room to work with and a nice straight length of hose). Cut the hose, removing about 25mm in the process to accommodate the length of the sensor adapter. Clamp the adapter in place with two hose clips (supplied). Top up the missing coolant. Feed the wire through to dash area and stick the display on with the 3M pad provided. And that's it!

FYI - Internal diameter of the top hose is 19mm.