1. Learn to type (fast) one-handed.
I'm doing this now while rocking the baby in his pram. It's a trick I picked up in hospital when I was on bedrest and forced to lay on my side for two months. Remember, you can use Caps Lock even when only writing the word "I". Doesn't work for those pesky quotes though. I can't guarantee accuracy either, but you can fix that when he finally passes out from screaming his head off. Which leads me to...
2. Close your ears. Don't ignore the crying baby--rock him, put the binky in his mouth, feed him and making soothing noises, whatever it takes--just don't let it interrupt your thought processes or the character's voices (remember, you're still typing with the other hand during all this). Good training is listening to hard rock while you write and slowly tuning it out. Other tips: baby slings and weight training for your biceps.
3. Use every spare minute. Priorities are the baby's care and play time, food, and and sleep (hah! good luck with that), but when that little guy is dozing, be it 20 minutes or 2 hours, write. There is no time for courting the muse here. Get it done.
4. Keep the muse fed. I said there was no courting her, no gentle routines to entice her into whispering in your ear. What you have to do is chain her to you like a slave.
5. Write notes whenever you're not at the computer, and keep pen and paper everywhere--even beside the change table (with hand disinfectant too).
6. Enjoy that lack of sleep. Sleep-deprivation, like alcohol, makes everything better--at least to you and Hemingway. But if you check your writing the next day and everything reads "feed the baby, feed the baby..." then you might be in trouble.