Hi,
Do you want to populate indexes and corresponding pages to TreeMap ?.
Then the answer could be,

1) create a simple map inserting all indexes and corresponding pages to the map.
and use constructor of TreeMap to create a new TreeMap using map as parameter to it.
eg,
Map map = new HashMap();
loop:
map.put(index,page);
TreeMap treeMap = new TreeMap(map);

It will simply sort your pages according to indexes in ascending order.

please let me know i have answered your question ?