dealing with MAC address

[ashtonn@gmail.com]

Hello,
I am trying to fill a packet with source and destination mac address.
The first 6 bytes hold the destination mac address and the next six
bytes hold the source mac address. In the code i am filling in the
first six bytes to broadcast address for the destination.

# fill in the destination address
data = array('B', '\0' * 512)
for i in range(6):
    data[i] = 0xFF

How do i fill in a command line passed mac address for source mac
address. The first six bytes of data[i] should contain destination mac
and the next six bytes of data[i] should contain the source mac
address.

Thanks,
Ashton