Float MAC address in Heartbeat format

It's been about a month where I've been working with "High Availability" on Elastix based on DRBD and Heartbeat. As you maybe be familiar with it, there is a file in Heartbeat called haresources that's used for assigning the primary server, replicated partition, starting services and finally creating a Float/Virtual IP address. In haresources virtual IP address define with a format like IPaddr::192.168.116.10/24/eth0/192.168.116.255 As this virtual IP address created it will be assigned with a MAC address exactly the same as real interface. Due to some problems on Voice Gateways, I think it's better to change the MAC address of virtual interface; but this changing should be placed on haresources and its format. What should I do?