prosetcl.exe Adapter_SetSetting <AdapterIndex> *SpeedDuplex <value>
e.g. To set adapter 1 to 100/Full...
c:>prosetcl.exe Adapter_SetSetting 1 *SpeedDuplex 4
e.g. To set adapter 1 to auto negotiate...
c:>prosetcl.exe Adapter_SetSetting 1 *SpeedDuplex 0