Performance Alert for Portion of Transaction

Hello, 

New to Alertsite. We have a monitoring requirement that states if our order page does not respond in 3 seconds, we need to fire an alert. We have our transaction broken into 4 steps, but the specific portion of the transaction we need to alert on is lumped into step 3. So when I create the performance alert, the alert would be inaccurate. 

Is there a way meet this requirement in alertsite. 

Note: I have attached a screenshot of the portion of the transaction I would like to track.