Thanks Spuluka. Would something like this work (using static routing for now, will have to modify for BGP):
Device A
set nsrp cluster id 1
unset nsrp vsd-group id 0
set nsrp vsd-group id 1 priority 1
set nsrp vsd-group id 1 preempt hold-down 10
set nsrp vsd-group id 1 preempt
set nsrp vsd-group id 2
set nsrp vsd-group id 1
set nsrp monitor int eth1/2
set nsrp monitor int eth2/1
set nsrp rto-mirror sync
save
Device B
set nsrp cluster id 1
unset nsrp vsd-group id 0
set nsrp vsd-group id 2 priority 1
set nsrp vsd-group id 2 preempt hold-down 10
set nsrp vsd-group id 2 preempt
set nsrp vsd-group id 1
set nsrp monitor int eth1/2
set nsrp monitor int eth2/1
set nsrp secondary-path ethernet2/1
set nsrp rto-mirror sync
set int ethernet1/2 zone untrust
set int ethernet1/2:1 ip 1.1.1.2/30
set int ethernet1/2:2 ip 1.1.1.6/30
set vrouter trust-vr route 0.0.0.0/0 interface ethernet1/2:1 gateway 1.1.1.1
set vrouter trust-vr route 0.0.0.0/0 interface ethernet1/2:2 gateway 1.1.1.5
save
And then cable Device A Eth1/2 to one of the carriers routers and Device B Eth1/2 to the other?