There are some boots like full tilts which can be slightly easier to get on, but they will only work for you if they fit your feet. How much flex do you have in the ankle? You will prob need some pretty spefic footbeds made to help you aid flexing the boot. If you cant flex your ankle enogh to get in a boot you will definatly need some work doing.
Try to find the best boot fitter in your area, or book a trip to see someone good. Its the only advice we can really give you.
What technique do you use to get the boot on. Most people do it wrong, they just pull the tounge foward. Thats the wrong way to do it, you want to instead use the tounge to open the top of the boot. To do this you want to pull the tounge to the side not forward.
Certainly though for a bad ankle it will be well worth getting some good footbeds, so prob your best bet will be to take your current set up to thebest bootfitter you can find, and have them see if everything is working as it should. They can also show you the correct way to put your boots on.
Thanks guys i got a pair of full tilts and they are super easy in and out!