How to use xterm and picocom for serial VT52 emulation

First open xterm in VT52 mode:

xterm -ti vt52 -tn vt52

Inside the xterm terminal window, open picocom to access the serial port.

picocom -b 115200 /dev/ttyACM0

While the serial port access will be handled by picocom, the terminal emulation (i.e. escape code interpretation) will be handled by xterm.