Converting Binary Search Tree into Decreasing Ordered Linked List
The idea seems alright, just a tiny bit of comments:

InsertFront(T) should instead be InsertFront(T.root) (or you will get a linked list of trees).
As is, your function takes two arguments: a tree T and a linked list L, and add the in-order of T in front of L, and returns nothing. If you want a function that returns the in-order, you could add:

inOrder(T){
   L &lt;- empty linked list
   toList(T, L)
   return L
}