How to get opportunity contact role in Marketo?

I know that you can see the opportunity contact role on the opportunity tab, but it appears that you can't filter on it at all. I have raised a case and support has told me that the role comes across to Marketo but is not available as a filter. I want to be able to pick up contacts who role is something like accounts/legal/purchasing to exclude them from nurture, but I can't find a way to do this. FYI we only have SFDC Professional Edition, so I can't use a workflow to update a field on the contact, so frustrating! Does anyone have ideas of how I could get this info into Marketo short of having to run a regular report in SFDC and load it as a list into Marketo? I would really prefer a more automatic solution but I can't think of one.