To open new editor pane, use "NPP_SENDMSG WM_COMMAND IDM_FILE_NEW".
To get the Console output, notice the usage of "NPE_CONSOLE v+" and "SEL_SETTEXT $(OUTPUT)" [4.6.3].
To sum up, the following NppExec script should be used:
// enable the $(OUTPUT) variable NPE_CONSOLE v+ // your command here... for example, let it be "cmd /?" cmd /? // open new editor pane NPP_SENDMSG WM_COMMAND IDM_FILE_NEW // set the text in the new editor pane SEL_SETTEXT $(OUTPUT) // finally, disable $(OUTPUT) variable NPE_CONSOLE v-