Create a custom field and put this the in script field:
{
watts = streams.get("fixed_watts").data
w30 = icu.stats.calcMovingAvg(watts, 30)
tss = 0
for (let i = 0; i < w30.length; i++) {
w = (w30[i]/icu.sportSettings.ftp)**2;
tss += w
}
activity.icu_training_load = tss/36
}
It will update the Load after re-analyzing the activity or for new activities.
Or maybe @PiotrekNL will make his script public, so anyone could search for it and add it 