Please help: how to zoom in and out with HTC Diamond 2

Hi there,

I was happely using MyMotion on my HTC Touch Cruise. My Cruise sadly died from a very heavy rainshower. So now I bought myself a HTC Diamond 2. The Diamond 2 does not have hardware up and down buttons or a scroll wheel like the Cruise had.

So now I just don't find a way to zoom in and out.

Please help! Without this ability MyMotion is useless and it is by far my favorite program.

Johan