Not as an individual. There are 1/2 day tickets available to some conventioners, if the convention organizers choose to obtain them.
Depending on the timing of your trip,(Sept through Dec) you may be able to attend a party. (Mickey's Not So Scary Halloween Party, or Very Merry Christmas Party) Party tickets are generally a little cheaper than a one day ticket (by about $15).
If you attend a party you can usually enter the park at 4 (even though the party starts at 7) and stay till Midnight. The nice part is that after 6 the start to clear then park of any non-party goers, so the crowds are usually lighter. Keep in mind, the Parades and fireworks are holiday themed during these parties.