I have been studying all the different modes on the Chronus chess clock.
It wasn't clear to me at first that the clock supports increment, but it does. The way it supports increment is to have two time controls where the first time control is the starting time and the second time control is one that repeats over and over and has a time equal to the increment. For both time controls the number of moves has to be set to 1. The Chronus clock has a mode designed specifically for this where you don't have set the number of moves and that mode is CH-P5. (The "CH" is for CHess and the "P" is for "Progressive".)
For simplicity, for anyone at the tournament who is not sure how to set their clock, I would tell them to use CH-P5.
An alternative to using CH-P5 is to use CH-P1. The disadvantage is that you have to manually set the numbers of moves to be 1 for both time controls. This mode has one advantage in that it displays a "flag" when the time runs out, so it is my preferred mode.
Personally I think that it is better to set clocks with all beeps off so as to not disturb other players.
The Saitek Competition Pro clock supports increment by using one of the "Fischer" modes listed on the bottom of the clock. Either 4A or 4B mode should work. The cheaper blue version of the Saitek clock does not support increment.
The DGT North American clock should use mode 14.
As far as I can tell, the DGT 2010 clock already has a preset for 90 minutes with 30 second increment. It is mode 17. If a different increment time control is desired then use mode 18.