Juniper MX map multiple inner tags to one outer tag

I have a Juniper MX in a lab terminating pppoe sessions. I'm using s-tag/c-tag setup.

s-tag = 175

c-tag = 900

set interfaces demux0 unit 175 vlan-tags outer 175 set interfaces demux0 unit 175 vlan-tags inner 900 set interfaces demux0 unit 175 demux-options underlying-interface ae10 set interfaces demux0 unit 175 family pppoe dynamic-profile BasicPppoeProfile 

This config above works fine.

How would I be able to map multiple c-tags (9xx) to one s-tag (175)? e.g. instead of just 900 I would have 900,901,902,203 etc. I've had some looking and I can see there is something called vlan-map. Not sure if I'm on the right track there. Does anybody have a working example of this?

Thanks