well this is what i finished doing:
The first part is the same
self.outliner = QWidget()
self.outliner.setObjectName("outliner")
self.outLayout = QGridLayout()
self.outLayout.setContentsMargins(0, 0, 0, 0)
self.outLayout.setObjectName("outLayout")
self.outliner.setLayout(self.outLayout)
then I "translate" Pyqt to maya to be able to assign the layout with any extra code
panel = mui.MQtUtil.fullName(long(sip.unwrapinstance(self.outLayout)))
cmds.setParent(panel)
if cmds.modelPanel("outL", exists=True):
cmds.deleteUI("outL")
outL = cmds.outlinerPanel(mbv=False)
cmds.control(outL, edit=True, visible=True, p=panel)
ptr = mui.MQtUtil.findControl(outL)
Transform a Maya widget to a QWidget
self.outPanel = sip.wrapinstance(long(ptr), QObject)
And Finally add the Widget to my Layout
self.outLayout.addWidget(self.outPanel)