I assume all the yeast sediment is still in the wine, otherwise, surlie would have no affect. make sure you sulfite at the end of MLF to kill the mlb completely.
I have heard of some wine makers very successfully doing surlie on a Pinot Noir, but it is not a normal practice. If you do it, monitor (taste) it as you go to make sure you like the results.
You don't necessarily have to stir it. The stirring part is called batonnage. If you don't stir, you will end up with a softer result, but it will take longer.
If you stir, I would stir once a week for the first month, then move to every two weeks the second, then go to once a month. Of course it all depends on how long you want to do surlie. Three to six months is a good number.
You might split the batch into two; do just surlie on one and surlie/batonnage on the other, then blend. You will loose some of the fruitiness of the wine with surlie, so another approach is to split; do surlie and possibly batonnage on one and leave the other without either; then consider blending the results.
Again, monitor by tasting each time you stir. The yeasty, nutty, biscuity taste of surlie can get strong rather quickly.
