how to modify terrain property dynamically using keyboard?

[maddy]

In one among the tutorials, a water 'terrain' is created and then rendered.using this part of the code

mesh = smgr->addHillPlaneMesh("myHill",
core::dimension2d<f32>(20,20),
core::dimension2d<s32>(40,40), 0, 0,
core::dimension2d<f32>(0,0),
core::dimension2d<f32>(10,10));


and i want to modify the terrain's properties(dimensions) at runtime ........... by assigning some variables like a,b,c ........ and controlling their values at runtime using keyboard(say)

so how to do this?