Thanks Jason for your help.
This works:
</head>
<body onload="WA_FilterAndPopulateSubList(groups_WAJA,MM_findObj('UserCompany'),MM_findObj('GROUP_ID'),0,0,false,': ');WA_setSelectionsInChildList(MM_findObj('GROUP_ID'),<?php echo $row_WADAusers['GROUP_ID']; ?>)">
<div id="outerWrapper">
While this does not work:
<script type="text/javascript">
WA_FilterAndPopulateSubList(groups_WAJA,MM_findObj ('UserCompany'),MM_findObj('GROUP_ID'),0,0,false,' : ');WA_setSelectionsInChildList(MM_findObj('GROUP_I D'),<?php echo $row_WADAusers['GROUP_ID']; ?>)
</script>
<!-- InstanceEndEditable -->
</head>
<body>
<div id="outerWrapper">