it's not written in assembly but in Hexadecimal which they denote with the h after the number 80h 02h 00h 7Eh
which traditionally is represented with 0x before the number in programing - so you would do
CO2CGM_Serial.write(0x80); // sends 80h
CO2CGM_Serial.write(0x02); // sends 02h
CO2CGM_Serial.write(0x00); // sends 00h
CO2CGM_Serial.write(0x7E); // sends 7Eh
where CO2CGM_Serial is the Software Serial object you declared