how to get multi selected row values from a table of fusion screen using sandbox page composer

We have a requirement from Oracle fusion process requisition screen, when user selects the multiple rows from search results of table in process requisition screen. we need requisition number values of those selected rows of the af table in fusion screen to be accessed through a custom html and javascript code which embeds custom button(View uom) on the screen. through sandbox approach - page composer tool structure option - we could not find any edit property on the af table like row selection listener to add custom script in EL expression . also the fusion UI source code is not accessible to add below code to register a js client listener method on af:table of the process requisition screen. <af:clientListener type="selection" method="jsRowSlctnListnr"/> The other method we tried to access the multiple selected rows of table is through the row bindings of the table on fusion screen by row selection listener bindings "#{bindings.RequisitionSearchLineVO.collectionModel.makeCurrent}" from custom button code of html and javascript and didn't got the multi select row values of the table. kindly suggest solution on this.