My son normally fights, so we have a new routine. I got some inexpensive clippers from the grocery store that have a little teddy bear on them, so I tell him the teddy bear is kissing his nails to cut them (he is almost 3 and very very strong), and we sing a stupid song "one little, two little, three little fingers, four little five little, six little fingers," etc. (same for toes) while clipping them. If he gets frustrated and tries to fight, we pause and I show him the bear and remind him that the bear needs to finish kissing his fingers. We use "kissing" because it is touch but more gentle, and he does know that it is also cutting. I have never tried doing this while he was sleeping. If he is really irritable about it, I start to cut mine or tell him I'm going to cut his baby brother's nails first.
Another option is to try nail scissors. You can get very cute ones where the handles are a butterfly and it is very comfortable for the child. Hope these ideas help!