Sorry I can't help, it's something I'm keen to try also although I've yet do my own investigations.
I'd be cautious of asking by phone/text as I can imagine some WG's would assume I'm a timewaster so I'll try emailing them via AW as at least I can search for those with it listed on their "likes" giving me an opener e.g "I wanted to enquire about one of the services you have listed" etc though I suspect most will have ticked the box with no intention to actually offer it.
If you've already been making enquiries, how's the general response been?
I'll update if I have a chance to make some enquiries..