To program your SP50, use the following pinout:
Power the radio with jumpers then connect the ground of the programming cable (pin 1) to the radio ground and connect the data wire (pin 15) to the bottom side connection on the radio.
You can make a nifty programming interface by getting ahold of a couple of standard chargers and robbing the pieces to make a programming stand.
With respects to the "factory type" plastic support for the programming stand, it is a Motorola part, but is not available from Motorola. They know how simple it would be to order the parts to compete with their price on the programming stand.
One still can order 2 standard chargers, remove one of the charging contacts, and use it for the programming contact if you get desperate. There are enough parts to make 2 programming stands out of 2 standard chargers. The standard chargers are $18.00 each. Its just that you are not able to have a standard charger to charge the radio and have it as a programming stand at the same time.