Graph in time

I need help

I'm trying to make a graphic that is changing with time, one of the value in this graphic it is the time, I used the example that has qwt about cpuplot to bring up the hours in the axisBottom.
I have two problems or questions to make to someone:
1.-Can I display the values in an array axisBottom where time has been introduced in hour format, without performing any calculation?. I know that i can introduce only double array in a plot. How can I do?
2.-I need to use zoom's property into the graph and I only can do in the y-axis, the x-axis shows all values as if the zoom was not realized.
what we need is to make a graph where the data are collected from two arrays having as xBottom value in time. Display the zoom on the two axes, anyone know how to do this?