There is no auto add dkp per hour available.
There is however a timer you can start which will take a snapshot at any given setting you give.
just type: /grss starttimer -> this will make a little popup window appear where you put in the number of minutes you want.
I suggest you then create a destination called timebonus or something like that, so you can easily link the auto snapshots to the value you set.
I hope this helps - if it was what you were looking for anyway
/Misen