SpringBoardAccess cydia tweak allows to control status bar icons from background daemons.
The SpringBoardAccess provides access to SpringBboard functionality for non-GUI applications such as background daemons. So far, it allows to add and remove icons to the status bar by name.
The icons already have to be present in /System/Library/CoreServices /SpringBoard.app and be named “Default_NAME.png” and “FSO_NAME.png” similar to the existing files. The FSO files are used with a black status bar, e.g., in the SpringBoard, the Default icons are used when the gray status bar is shown, e.g., in normal apps. A SpringBoardAccess-test command line utility is included for testing. To toggle status bar icons from a background damon, check out SpringBoardAccess.h in the SpringBoardAccess component of the BTstack project at http://btstack.googlecode.com. For more info please join the BTstack developer mailing list.”