Spreading the frame will not be difficult. Just remember to do it equally from both sides to preserve the centerline. There's also one more step fro a proper job, and that's to re-establish the parallelism between the dropouts which will now be slightly opened into a "V" A special tool is required, so unless you have a friend who has one, you might shop around for a LBS to do the spreading for you.

You might be tempted to take a shortcut and simply spring the frame and force the wheel in, but that's not a great idea since it doesn't address the dropout parallelism.


BTW- I said "shop around for a LBS" advisedly. Spreading a rear triangle is the kind of job where you'll get quotes all over the board, so do your homework, and look for someone who'll do it right for a fair price.