Inline skate tutorials (txt)/
The Backward Crossover is the forward crossover, but in reverse.
Anyway, while doing forward crossovers, you'll put more pressure on the rear wheels and less on the front wheels. In short, you'll tend to push through the heel.
Backwards is the direct opposite. Going backwards you'll use your forefoot to put pressure on the front wheels. This is the key.
To do it, you'll have to bend your knees a little more deeply. Give this a go and you'll see how much more stable and comfortable you are.