Hi Ricky,
yes this is possible, !
Assuming your table "MyTable" has repeated rows "Row" with a textfield "Name" the script in you add row button would look this way:
// Add 1 row
MyTable._Row.addInstance(1);
// Set focus on textfield in newly added row
xfa.host.setFocus(xfa.resolveNode("MyTable.Row[" + _Row.count - 1 + "].Name").somExpression);