Pretty easy if I am understanding correctly, create a new event:
System > Compare Two Values
For the First Value type ObjectName.Platform.VectorX
For the Second Value Type 0
And choose the comparison in the middle dropdown (Greater Than, etc...)
To make this easier, notice that when you are clicking in the text box for the first value, that there is a semi transparent window above the current one, mouse over it and you will get access to all the objects and their expressions...