I have created a program of high frequency hits using GX and Sample Digitizer. I want to run this program using a remote killing preset on my XM generators. What changes do I have to make in order for the XMs to be able to produce these higher frequencies

You just need to ensure that you have a wave cycle multiplier of 4 enabled on the waveform you are using.

If using a standard square wave, follow the line over on the settings tab, and change the value for X from 1 to 4 for instance.

You will note some waveforms have a built in wave cycle multiplier greater than 1, like the Square H Bomb (16). If you were to use this waveform, it will have no issues hitting those higher frequencies.

To ensure that the setting takes, make sure you start by selecting the preset, then add your frequencies, then check/modify the WCM on the settings tab, prior to loading to the generator.

If you have already loaded to the generator, you can click the control window button for that generator to load the settings. Make sure the generator is stopped or you won't be able to upload the modified settings. Then click the settings tab and modify the value. Then go back to the control tab, click allow generator overwrites, and then reload the same settings (modified) back to the generator.

For more details, please check the link:
https://www.spooky2.com/forums/viewtopic.php?f=6&t=9753