Trigger a work flow for VL32N or VL31N

Hi

I need to trigger a workflow for T code VL32N i.e. inbound delivery. I've found a business object BUS2015 but it has got no event by which a workflow can be triggered when inbound delivery is changed or created.

Is there any class which can help ? I've tried to find out through SWEL but it didnot help.

What else can i do ?

Regards

Anik.