First you have to konvert the contense of the register to charakter format,
so that you can print or read it. St-Command only stores the content in
binary format. Use CVD command. Then move your WorkingField to the
WTO-Command to the specific offset. Then execute WTO.
MVC WTO01+XX(YY),WorkingField
WTO01 WTO 'THIS IS REG04: XXXXXXXX'