As has already been said they is nothing you can do yourself to sort it out.
Your boots may be too big, too small or just require fitting. A good start would be to take them to a good boot fitter and have them see if they roughly fit your foot. If the shell is teh correct size then the first thing yo should do is buy a good custom footbed. The Sidas Conformable as the best available in my opion. A custom footbed will support your foot in a neutral position, often making your foot shorter. This may be all you need. If they still feel a little tight then you can get the toe box of the shell stretched. A good shop would usually do the stretch for free if you buy a footbed at the same time.
So overall no here is not really any thing you can do at home, and to your question about gel inserts,no they prob wont help, a good stiff custom footbed is usually going to help allot more.
If your boots are too big, there is not much you can do unfortunately.