The proper tool is a U-shaped 2 prong device which slides into each hole releasing the retainer tabs. It also hooks in at the back and allows you to pull the unit out of the dash.
I ended up using a length of whip aerial which I had chopped off my VHF aerial when tuning it. Something about 1mm to 1.5mm dia. should fit, a coat hanger may be a little large. You'll need 4 lengths at a min of approx. 100mm. This will release the retaining tabs but you'll still need to gently prise from the dash - easy.
If all to hard, pop into a LR Dealer and ask them to pop it for you.

