How to fast set hot corners in Mavericks?
Before Mavericks there was indeed a property in System Events called "Expose preference". 

Since 10.7 Lion, Expose was replaced by Mission Control, so this must be a remaining of this past time (The pref pane is called Expose.prefPane). 

But in Mavericks this property was removed and not replaced. 

tell application "System Events" to get properties returns 


security preferences
network preferences 
screen saver preferences
appearance preferences
CD and DVD preferences
dock preferences


And none of them has access to the hot corner properties. 

So, no it's currently not possible to do the same thing. Or to be more precise, to do it without UI scripting. (BTW your script does not use UI scripting features).