The other method would be to point the toe of the boot into your stomach and draw back the liner out towards you. Or if you have a spare set of hands, have someone open the lower overlap which will allow the liner to lift out much easier.
Often when they become sticky, it id because they are releasing some of their adhesive into the fabric. Is this an older model Salomon or Rossignol? For cleaning, I suggest just hand wash in soapy water and get them in the sun for a day or two. But if they are really sticky, they might be finished. :(
To dry them properly. :) If you take them out, the liners will dry inside and out. Also no moisture remaining in between liner and shell. (which will mean cold feet the next day) It will make your liners last much longer and prevent them from becoming rank and stinky. Also the foams wont break down as fast, compared to if you leave them inside the shells.