multiple source address in one firewall rule?

Can I add multiple mac-address' in a "source" for one firewall rule?  I have a few, specific devices that I want to have the same rule apply to.  It would be easy for me to add (and maintain) something like the following:

rule 500 {
    action accept
    source {
        mac-address xx:yy:....
        mac-address zz:qq:....
    }
    ...
}

(Or maybe it allows for comma-delimited list of mac-address on one line or something?)

Thanks for any tips/tricks/pointers!

-AJ