PostEvent doesn't immediately invoke a sequence or macro. Instead, it posts a "key down" event for later consumption by Hypercard. So a HyperTalk fragment like the following won't work:
PostEvent "InitRulers"
open "MacWrite"
because nobody will see the event. The trick is to have the sequence or macro already running when you issue the open command. I use the following trick:
Create an invisible button called "Macro". Every sequence starts by clicking on its location. It has the open command in its mouseUp handler (if necessary the application name can be saved in a global variable). Then the following fragment can be used:
set the hilite of button "Macro" to true -- show it
PostEvent "InitRulers"
and the sequence will take over. In QuicKeys, the sequence and its components will have to be Universal, not program-specific.