Threshold based on CPU wait with complex math. Possible?

[stormonts]

I have been asked if it is possible to create a threshold that would alert when the "CPU Wait" is greater than the sum of "CPU System" and "CPU User" * 1.5.

Since the values that come from SNMP are raw and need to be divided the number of processor in the system (which means one threshold for each configuration of server).

It doesn't look like a CDEF has the ability to add two different values from an indexed data source (in this instance I am using the "Fridh - ucd/net -systemStats" data template which stores, ssCpuRawSystem, ssCpuRawWait, and ssCpuRawUser). I don't think an RPN expression in the threshold would work either?

If so, math would be something like ((ssCpuRawSystem + ssCpuRawUser) / 16) * 1.5, but I have no idea how to get that into a CDEF/RPN.

Or is my only (saner) choice to go with a exact high threshold value of say 30% and base then use then specify a CDEF in the "Data Manipulation" section to divide by the number of processors in that system to get me the correct wait value?