Trenchboy, We had some leylandii logs given to us, so seasoned them down for 2 years and burnt them last winter, they were the lightest logs we have ever had, I could pick up a whole massive stump by myself! If I remember correctly they burnt quite quickly, but if you are like us, it was the, it is free, so who cares attitude!
We have 3 in the garden that I cut down quite radically, to about 2 foot, and yes the rotten things are sprouting again >:(
I suppose you could get some stump stuff, can't remember what it is called, and put that on them with a placcie bag over the top?
GROWING SUCCESS DEEP ROOT TREE STUMP KILLER, by growing sucess, is the name, I have seen it at many garden centres, Piccie of product here
http://www.ahsdirect.co.uk/product/227/82They make good seats too!
Hope this helps DP