The status bar icon listen for profiles changes.
But if you want to control the profiles settings from your
app or widget, you can use dbus-commands to
control profiled (the systems profile daemon):

get the list of available profiles:
dbus-send --session --dest=com.nokia.profiled --type=method_call --print-reply /com/nokia/profiled com.nokia.profiled.get_profiles

get the current active profile:
dbus-send --session --dest=com.nokia.profiled --type=method_call --print-reply /com/nokia/profiled com.nokia.profiled.get_profile

activate the "general" profile:
dbus-send --session --dest=com.nokia.profiled --type=method_call --print-reply /com/nokia/profiled com.nokia.profiled.set_profile string:"general"