When the command window is open, commands can be issued. To change to 4-pin mode, APFC must be written to 1 (using STC2 command), which assumes the TAP state is starting from Pause DR.
Scan DR (2 bits of 1, end in Pause DR): Load CP0 with 2.
Goto Scan (Through Update DR to Pause DR): Complete CP0 by going through update.
Scan DR (9 bits of 1, end in Pause DR): Load CP1 with 9.
Goto Scan (Through Update DR to Pause DR): Complete CP1 by going through update.