We do this all of the time, This is what we do but I would be interested in other methods.
1. Remove component with BGA type rework station 2. Wick off lead pads only, verify/create even solder surface on the thermal pad on the board 3. Apply no-clean solder to the component pad (just enough to allow component to sit off of the board about .005-.010" 4. Align component (sometimes difficult) 5. Reflow part onto board with BGA station. The part will seat itself onto the board when the thermal pad solder reflows. This is how you verify that the thermal pad was reflowed and wetted to board 6. Hand solder leads
Hope this helps
Russ
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