It's actually quite easy. Open the workflow and double click the action that says "open URL" (the upper right one).
In the URL field (which currently says "busycalevent://new/{query}") you just append the keyword "in" and your location. Be aware that you have to URL-encode some characters, i.e. spaces become "%20". A list of those characters can be found here.
An example: if your location was "my sweet home", the URL field should be changed to "busycalevent://new/{query}%20in%20my%20sweet%20home".
Hope this helps.
I'm sorry. I don't know Daylite. BusyCal works with URL schemes, so you may try to look for URL scheme support in Daylite and build something like this yourself.