Create an Information WT (one that does not affect gross or net) to hold the hours in it's amount field.
Through a PCR, read the hours from the NUM field of the required WTs and transfer them into the NUM field of your Information WT. Through a PCR that will process your Information WT, use the following operations to transfer the value of the NUM field into the AMT field : AMT=1 MULTI NAA ADDWT *.
Create your special Cumulator in the /19x series, and mark only your Information WT to cumulate into it.