It is possible to place manual bets in live or sim mode.
Click the Manual Bets drop down arrow, this will open the manual bet panel.
Click the Back (blue) or Lay (pink) side of the selection in question and the manual bet panel will be filled with the correct details. You can change the price stake etc. Then click Place Bets.
You can submit multiple bets, back or lay on the event as long as it is open.