Hi Joachim,
I did not understand the scenario which you are using this requirement.
But I understand the requirement.
1) If you want to make "All Day Event" set as default i.e give the tick mark by default. 1st Check whether there is any option in the date profile, for the tick mark. If not, I repeat "if not" This can be done by component enhancement. Very small enhancement, CRM tech/webdypro person can do it.
2) If time/time to : 1st remove this attributes form the table view and check whether it is satisfing you requirement. If not this can also be set default by small enhancement by CRM technical person.
If required I will guide You further..
Rewards experted if it is helpful.................
Regards,
Sap Adherent.