[c-nsp] inter-as multicast

[Good One]

We have a BGP inter-as peering with one of our service provider over a sub-interface of a point to point link. And now we want to run PIM (between us and service provider) using a different sub-interface over a same point to point link. Someone told me that PIM is an intra-as protocol and can't be run between service provider. 
Now the question is .. what if we get a /30 IP-Address (keeping in mind that /30 belongs to service provider AS and they can see it in their IGP table) from the upstream provider and run PIM over it and then you can have a static IGMP join on your own router so that our own AS-IPs can get the multicast. 
thanks
regardsAndrew