Test the balloons on the tube to the maximally recommended volume, then fully deflate them
Lubricate the tube, then pass orally to a depth of 50-60cm
Insert air into the gastric aspiration port and listen with a stethoscope over the stomach and lungs. Inflate gastric balloon with 50ml air
Confirm placement with chest x-ray (gastric balloon in stomach)
Inflate the gastric balloon with air in 50-100ml increments up to the maximally recommended volume (250-300ml for SVT or 450-500 for Minnesota). Stop if resistance is encountered. Clamp the port
Further x-ray to confirm position
Pull balloon back against gastric fundus. Mark at the lips. Traction with 500ml bag of fluid and rope-and-pulley system
The oesophageal balloon should only be inflated if bleeding continues (inflate to 40mmHg)
The EMCrit blog has some further tips, as well as a video to help to explain the above steps more easily.