Nicholas, not sure if it's just the way you phrased your question but you can use titanium pots on alcohols stoves that don't simmer!
If however you do need to simmer,you could take a look at the Thermojet Stove, reviewed here on the site and also under the reader reviews section. It simmers perfectly, as well as boiling water like mad if you wish. A few users on the site however did have a few problems getting hold of one though (See the reviews).
Simmering, is generally a bit of a problem with alcohol stoves because 99% (My guestimate) don't really come with that ability. You could try increasing the distance between your pot and the stove if you have a stove that wont simmer, to drop the temperature although that might be a bit fiddly and not very fuel efficient.
Another option might be the NION from Minibulldesign. It will eventually boil water and keep it at a rolling boil but it puts out a lot less heat than other alcohol stoves (Takes water longer to boil) and therefore would be ideal for say cooking foods that will cook quickly at a low heat, a fried egg for example if you have that luxury on the trail!!!
I think the Thermojet might be your best bet though (IMHO).