Solders are available with many different melting points.
Here is how I would do it if the '06 has a built in lens....
First I would cut two diodes of the block with a band saw. Next I would cut into the block on each side of the diode till I hit, or very near hit, the diode rim. After cutting I would put the diode in the toaster oven at around 85 deg C. After say 5-10 min take the block out and try to pry the block apart at the cuts. It should be obvious at this point if the solder has softened. If not go up say 10 deg C, repeat.
I wouldn't try anything without the relief cuts due to the fact the diode are pressed in as well as soldered.