Another user gave me a link to an archived post (non-SS) about doing the method using charcoal. Copied and pasted here, edited it to remove things like links. I can attest to the claim that briquettes are much easier to light than lumpwood charcoal, which I found impossible to light in a chimney starter. I'm not sharing this because I believe every word, but because we need more info on this method:
First of all, you need to buy "premium" charcoal. The two most common type are lumpwood and briquettes. I would highly suggest to use quality briquettes over lumpwood. The consistency of briquettes make them a lot easier to light and they smoulder longer than lumpwood and burn cooler. They do have a bit less carbon content, but in the end it's not a big deal. Also, contrary to popular belief here, quality briquettes usually produce less smoke too.
Only use a chimney starter to light the charcoal. You may be tempted to use lighter fluid — but don't. This is the only way to ensure perfect glowing briquettes that will burn at the same rate. Just use some crumpled sheets of newspaper on the bottom of the chimney and light them with a match. It takes about 25 minutes to get them at the proper state. Once they are ready, you can dump them in a small portable charcoal grill [Edit: or metal/galvanized steel bucket or tray]. You want the charcoal to be fully white (45 minutes for Royal Oak Ridge) before you bring them inside. Don't put the cover on obviously. If using benzo/alcohol just go in, drink your cocktail and pass out. If not, let the charcoal sit for 20 minutes inside the room before going in.
1KG = 2.2lbs is plenty for a small space like a car or tent. If your room is bigger, double the amount. For 1KG you'd need approximatively 35 briquettes.
The location is obviously extremely important. The smaller the area, the better it is. Carbon monoxide will fill a small space at a high PPM much more quickly. It can also travel through walls so please make sure no one else is present. Apartment and hotels are a bad choice for this reason. They can also have CO alarms installed. Always make sure to seal the area well. Put a blanket under the door and use ducktape around door/window seams, fan vents, holes, etc.
Renting a minivan is a good option. You need to keep in mind the size of the charcoal grill. It's much easier to fit one inside a minivan than a small car. Ideally you want to put it at the bottom. The charcoal grill will be extremely hot so bring some oven gloves and position it in a way that it won't burn the interior of the car. I suggest to put it on top of a few bricks. Remove extra seats to get more space if necessary. Alternatively, use 2 or 3 smaller grills. In asian countries, you'll often see 2-3 small terra cotta grills used for suicide.
Tents can also be used but you need to make sure it has a flysheet built into the groundsheet to avoid air gaps. Look for a tent with a HH rating of 3000mmhh or more. This is a measure of waterproofness. The HH stands for hydrostatic head and it is the extent to which the tent material can withstand a column of water, in this case 3000mm of water. I would suggest to use a tent big enough for 3-4 man and place the grill on bricks and lay an extra layer around the edge. You don't want the heat from the grill to melt the tent. You need to use bricks or some sort of insulation at the bottom otherwise it might melt.
Only use a brand new grill. Do not cook food with it. Fat drippings and food will create smoke and ruin the whole thing.
I would recommend using benzo such as xanax, valium, ativan or klonopin mixed with strong alcohol to knock you out super quickly. If you can't, you could try alcohol with Doxylamine Succinate.
I wouldn't worry about buying a PPM monitor. You can die in less than 2 hours from only 1600 PPM. A meter is only useful in my opinion if you have a really big room. A small sealed enclosed space will fill with carbon monoxide quickly at 6000+ PPM. If you don't use any drugs to knock you out, I would suggest to let the charcoal sit inside the car, tent or room for 20 minutes before going in.
When you first lit the charcoal, the smoke could attract unwanted attention so please keep that in mind. Charcoal isn't expensive. Don't be afraid to do a few test runs. Different brands burn at different rate. For example, Kingsford Briquettes burn faster than Royal Oak Ridge so the timing won't be the same. If you use lumpwood charcoal, try to use chunks of the same size.
