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.
If you are looking for the programming cable for the SP50+, then you will want to check here.
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. It is possible to create a programming/charger stand... read on...
If you do your modifications right, you can make your dual purpose stand that will program the radio, if you drop the radio in, or charge the battery, if you remove it from the radio.
If you drop the radio in, it uses the side contacts (which are the ones used for programming). Although, if you drop in the battery, it uses two contacts on the bottom of the stand, therefore freeing the side contacts for being re-configured for programming.
It's abit of a pain to remove the battery all the time, but hey, it works!
Another thing you might want to consider is installing a DPDT switch on the two contacts, one position for charging and the other for programming.
The programming stand you buy from Motorola has a 12 volt input, which, according to the guy at the Motorola store will charge and power your battery at the same time, so I suppose one could buy/make the programming stand with the 12 volts, and hook it to 12 VDC, and you can then program and charge.