To modify the slate and burn-in for the tk-nuke-quickreview app you will first need to fork the app as you will have to adjust more than just a hook for this.
Once the app is forked you will need to modify the tk_nuke_quickreview.nk script that is located in the resources folder (https://github.com/shotgunsoftware/tk-nuke-quickreview/blob/master/resources/tk_nuke_quickreview.nk) and using nuke, arrange/modify the script to suit your needs.
If you are wanting to go a bit further and add new fields to the slate/burnin that are not in the default version, you can achieve this with the settings.py hook, (https://github.com/shotgunsoftware/tk-nuke-quickreview/blob/master/hooks/settings.py) and then use the new fields in the tk_nuke_quickreview.nk script.