Hi! I've had two dogs with this problem. I sat on the floor with them on their back in my lap. I gave a small treat before I trimmed the first nail, and then another treat after each nail was clipped. They soon began associating nail trimming time with treats!
I use the guillotine style clippers as they do a very clean and fast job and cause much less discomfort than traditional fingernail clippers.
Good luck with your baby!