It's not impossible, but no one will take responsibility Titleist recommends +/-2 degrees. Beyond that the potential increases that the surface along the hosel may crack. ...or worse.

Titleist doesn't charge for placing an order with custom specifications. The stock head is a neutral lie. If specified on an otherwise rack model in an order, they have a +2 degree lie head, so that one can be bent to a total of +4 from neutral as delivered.

That's a lot of movement, 2* is typically the max in house shops will do on cast clubs. Titleist starts off a bit more upright than most manufacturers so it would be like 4* up on a png or miz. I would have a clubfitter advise you on how much to bend them. Unless you are a very handle high player i suspect you are wanting them bent because you are toe heavy on your divots - if that is the case have your clubfitter check your club path, a severe out to in path will be toe down no matter how upright you go.

Not, recommended, but, not impossible- Titeist recommend 2 degrees maximum.

I've heard that the ability to adjust the lie depends on if the irons heads are forged. I am running into an issue with my T300 irons as well. They were adjusted +2* and now Im told they cant be adjusted anymore due to the heads not being forged.

There other stainless steel materials (such as 431 and 304) that other manufacturers will adjust at least 3 degrees- png using (heat treated) 17-4 stainless also goes beyond 3 degrees. There is always the risk of breakage when bending- perhaps Titleist will advise you of the material they use and you can make an informed decision from there.