u can do that by making a tree from the stack contents and then traversing the tree in either inorder or preorder as you wish
if ab+cd+* is your postfix stack(rightmost being topmost) the tree would be
Code:
*
/ \
/ \
/ \
+ +
/ \ / \
a b c d
to make the tree you will need to.....wel im not sure rite now what exactly but i'll get back to you in a day
im sure this cant be too tuf
another way i can think of is starting from the left and parsing the postfix string......
sorry my ideas are a little incomplete rite now...