How do you call a sub using Task.Factory.StartNew?

I am looking for the easiest way to call a slow running subroutine using the Task.Factory.StartNew and be able to cancel it?  I have the ASYNC CTP installed if that helps.

So something like this:
Start Slow Task 1 and Wait for cancel
Task 1 complete
Start Slow Task 2 and Wait for cancel
Task 2 complete
.....

Using .NET 4.0, VB syntax
Thank you for all your help!