I am not sure what you mean by "cumulative integral" but I have two suggestions for you to check out. In Signature Acquisition and Signature Throughput Processing we can do Level Calculations in the Online Processing, Section Settings. There are several settings that allow slow, fast and user defined time weighted sound levels. Whereas this is designed for microphone data, it will also work with vibration data. There is a User defined level that you can create which allows you to set the integration time and weighting since Linear weighting would be more appropriate for vibration signals.
The other option is to use the frame statistic "Integration" and then in the display you can sum it up cumulatively. The frame size used is 1/(frequency resolution).
This display is a 1x2 with the same Integration frame statistic curve displayed in both. The lower display has Forward Cumulative turned on.
Here are two examples of the first method with User Defined Levels in the upper display. And the same curves with Cumulative Forward turned on in the lower display.
You can see if either method meets your needs.