Documentation is available on page 190 of the IPCC Enterprise Scripting and Media Guide (Release 6). A sample script would not be much help since you will need to study your skill groups to arrive at a valid formula. You will also need to define the user variable to store the calculated value, which will be passed to the IVR sample script VISIBLEQ.aef.
It would be wise to check for zero as well as unreasonable low and high values. I suggest changing any value more than 600 seconds to 600 seconds or play a different message. We have experienced type conversion errors (and crashes) in the IVR when very high values were passed.
Hope this helps,
Greg