bondgirl77, my DD1 (SN) is very demanding, very direct in getting attention. She goes wild if you ignore her. Just do it. No-one can MAKE you give them attention. You just have to resolve that no matter what they do, you will remain calm and disinterested. Eventually, they will want to get involved in the positive thing you are doing.
what works for me, with my child, is that as soon as I see her doing something that I need to stop (be it that she has taken something that is delicate, or she is arguing with her sister, whatever), I quickly think of a 'consequence'.
I think, personally, that the consequence has to fulfil a set of criteria: Small (so that it doesn't escalate into a massive deal very quickly); immediate (3 year olds have a very short memory and association time-frame); 'doable' (don't threaten 'time-out' if you actually have to be out the door 10 minutes ago!).
So, I always start with (soft-voice) "DD2, put that back please" or "DD2, stop that, please", whatever.
Then, if she says 'no', or ignores me, I say "DD2222...." (solemn voice)
Then I move onto my count "Right. DD2. I am going to count to 3. If I get to 3 and you haven't done x, then I will...."
To be honest, half the time, now that they are in practice, I can use something as simple as "....then I will have to help you!" They are so focused on the 1,2,3, that they don't always really think about the consequence and weigh up the options, they just do it because they've heard "2" and think "Oops! 3 is next!!"
If they are being more determined, (and mine are headstrong little things), I find that I need to have a 2nd consequence. So, say I want them to go inside. I say "blah blah blah, you will sit on the naugthy step". I count to 3, they ignore. Right, DD2 must sit on the naughty step. If she got up, I would sit her back on the step, reminding her that I decide when she gets down. Her time starts again. Each time she gets up, I would calmly, firmly, direct her back to the step, and after a few times, I would say "if you don't sit on the step, you won't have your yoghurt, or whatever." All the time, I would be giving LOTS of attention to my other children.