Terminal command to address specific interface

I'm trying to run a ping test using Terminal running on a Mac connected to an external streaming device.

No problem getting into the device using ssh, but then hit a problem because the default interface on the device is for management functions and doesn't reach the outside world.

The valid interface is named mtpp0

I'm told this works in non-Mac environment:

# ping -I mtpp0 www.blah.com

PING www.blah.com (__.___.___.93)

any ideas? thanks