The answer to that is going to depend on a few things.
First, it matters what you're willing to let yoru failure state be. Either you want a raise, and to stay on with the company, but you're willing to suck it up and deal on the salary if you have to, or you want a raise and to stay on with the company, but if pushing for that raise loses you the job, then you're willing to accept that.
Second, it matters who your bosses are and how large the company is. The world where "how much do you get paid" is determined by your direct superior, and they care about your morale is a very different one than the major firm where those decisions get made at a much higher level and/or an HR office that you almost never interact with, and they're both quite different from a case where you on a first-name basis with the CEO but he has no sympathy for you.
Let's look at the breakdown, then.
- If you're in a large company, you're pretty much done already. They have a strong institutional incentive to not respond to attempts to renegotiate salary, and for the most part they won't. If you decide that the job simply isn't worth having at the current rate, then you might be able to figure out who has the authority to approve such things and talk with them, but understand that the kind of leverage you'd have to bring to bear to make this happen means that losing the job (either on the spot or shortly thereafter) becomes the likeliest result. If your direct superior is sympathetic, you could talk with them, and try to ask them to try to get you a raise, and you migth be able to convince them to help you out on that one... but there's a very good chance that they will fail, and nothing will change, even if it starts out lookign promising.
If you're in a small, sympathetic company, then you can go talk with them. Explain your frustration. Express that the job that you now have requires many more hours than you'd understood it to when you made your initial request, and that the combination of that and the fact that your'e paid less than your subordinates is eroding your ability to be happily productive. See if they'll help you. They'll probably at least be willing to talk about it.
If you're in a small, unsympathetic company it's sort of in the middle. If you actually care about keeping the job even if you cannot get a raise, then you're done. There are no techniques here that are even moderately safe. On the other hand, the institutional incentives are lower than with a larger corp, and you've got better chances overall. You'll know your target audience better and can thus tune the approach. You can speak with them more easily. Finally, and perhaps most importantly, they're more likely to actually need you.
It's risky in most cases, impossible in some cases, but not impossible in all cases.