there are several ways to set L/R locators
1:you can select an event and use the P key to move locators to events size
2:you can use the range tool and use the P key
3:for entering locators position only using the keyboard’’ there are commands on the Key commands editor.
for example search for “Enter left locator” command and assign key command to it.now you can enter only with keyboard the value of the left locator.do the same for the right locator.
4: click with left mouse on the rouler while holding Ctrl/Alt to set L/R locators
there are other options also ,try to search on the key commands editor with “locator” and see what options it brings to your needs