It's very simple. Edit the QML file (path kindly provided by juiceme, quoted in my post) and find the line that says "width: parent.width - (Screen.width / 5 * 2)". It's on or around line 137. Change 5 to 10. Restart lipstick. If you don't know how, restart the phone.

Please note that the change does have an undesired side effect that your email, SMS etc notifications now may overlap with the date text. Further tweaking is in order to move them a bit further down.

Please note that fiddling with your system files like this may render your phone unbootable. Only attempt it if you understand the risks involved.