In Entourage 2001 & X, you could double-click a certain day in the Calendar
to have a new event window open set as an "All Day Event".
In Entourage 2004, you can run this script:
tell application "Microsoft Entourage"
open (make new event with properties {all day event:true})
end tell
Copy and paste the above three lines of text into Script Editor
(/Applications/AppleScript/Script Editor). Go to File > Save As, and save
it to /Users/<Your User>/Documents/Microsoft User Data/Entourage Script Menu
Items/. Then, in Entourage, you can go to the Script menu (to the right of
the Help menu) and select the script you just saved to open a new all day
event.
You can also assign the script a keyboard shortcut. Simply add a backslash
(\) to the end of the filename and type the keyboard shortcut you want. "C"
is "Control", "M" is "Command", "O" is Option, and "S" is Shift. Be careful
not to assign one that's already assigned to another function in Entourage.
For example, you could call a script
New All Day Event\msE for the shortcut Command-Shift-E
New All Day Event\mcA for the shortcut Command-Control-A
More information about naming scripts is in the Entourage Help (Help >
Entourage Help) article "About the script menu".