Sorry to reply this late...have already you subscribed to advfn? If not, wait for a while..recently it hasn't performed properly..lots of complaints..
As for SEAQ...you see a list of MMs providing their bid and offer prices..you can't read as much information as you read from SETs, but you can still check if the price is ticking up..say how many of them has increased/decreased their bid/offer prices..that tells me if the price is ticking up or down..also you can check how many of them is offering the lowest offer price..if many then you won't expect an imminent rise, if only one for example and the price is ticking up and you have positive news/sentiment confirmation then the price might rise soon..the same works the other way round ie price going down..only one MM offering the highest offer price and there is a gap between him and the others with the price tickin down..further downwards price action could be soon..
Just a few points from those I folow..only you need to watch the action for a while to get the feeling and you need to have studied your lesson regarding that particular stock..plus if you're not a day/swing trader or trading short term, then don't bother I'd say...
Hope this will give you an idea, as I am notan expert on it..just sharing..it could be more helpful if you come up with concrete questions..or pop in the chatroom, choose a few stocks, watch them on L2 and we'll discuss the price flow..
Well good luck..