Making setBadgeLabel: work?

Recently I’ve been trying to use setBadgeLabel: on OS X, I’ve declared it this way:

Soft Declare Sub setBadgeLabel Lib "Cocoa" Selector "setBadgeLabel:" (tile As Ptr, s As CFStringRef)

Sadly, no matter how hard I try, I can’t get a Ptr for App.DockItem.
Am I doing something wrong? Any suggestions?

Looks like it has been added to macoslib recently…