Thanks, that suggestion worked well. Here's a code sample in case anyone else wants to do something similar:
@class custom_table(QtGui.QTableWidget):
def __init__(self, parent=None):
QtGui.QTableWidget.__init__(self, parent)
self.chkbox1 = QtGui.QCheckBox(self.horizontalHeader())
def resizeEvent(self, event=None):
super().resizeEvent(event)
self.chkbox1.setGeometry(QtCore.QRect((self.columnWidth(0)/2), 2, 16, 17))@
The "(self.columnWidth(0)/2)" keeps the checkbox in the middle of the column header.