A writ of possession might normally be stayed if there is a case of hardship: it might be the middle of winter, the tenant has no other place to go, and might need more time to find a new place. However, even if there is hardship, the tenant would need to post a bond and pay rent to the court clerk to get a stay of the writ. Otherwise, it's out.
The situation at St Mary of the Angels is different, since no one is living on the property. In addition, there is ongoing damage to the property owner (the vestry), which can't hold services on the property or rent the commercial space. As a result, the squatters can't claim hardship or damage, while the owner can. The squatters would need to appeal the writ based on a legal error by the judge.
They will first need to ask the trial judge for a stay, which is pretty unlikely. They will then need to ask the appeals court for a stay. Whether the appeals court grants a stay will depend on whether it thinks no damage will occur to the owner if the writ is stayed pending appeal. However, there is ongoing damage to the owner and no direct hardship to the squatters if they are evicted, since they aren't living on the property.
In addition, the appeals court has already addressed the law involved in the Rector, Wardens, and Vestry cases. An appeal of the decision and judgment in the September trial is not likely to succeed with the appeals court that has already ruled on the same issues.
I suspect there will be piddling little delays, five days here, ten days there, but the writ is going to be executed. All that will happen is more delay and more expense.
I'm starting to get little signals that the squatters and their supporters are getting rattled. What's at stake? Good question; inevitably, we're going to find out.