Using both Three Way Calling and Call Waiting

I am using Asterisk 1.8.0 and Dahdi 2.4.0 with a TDM410P using 1 FXO module and 3 FXS mdoules. If I enable Call Waiting on one of my FXS ports I can answer call waiting calls incoming on the FXO port using the flash hook. If I enable Three Way Calling in addition to the Call Waiting on the FXS port, I can no longer answer incoming call waiting calls using the flash hook on my FXS ports. Any attempt to answer the incoming call waiting call using the flash hook results in a dialtone becuase Asterisk is starting a three way call. Is there a way to enable both of these features at the same time or are the features doomed to conflict in this configuration?