If you are just not strong enough, it isn't worth getting hurt over. Now, having said that, I would tie her front feet together while she is standing. Have someone hold her or tie her to something what will hold her. Be ready to make slack when she fall down. Now, tie her back feet so they are hobbled but where she can still stand. Take hold of her front feet and push her over. When she goes down, put your weight across her neck and hold her there. Now, tie all four feet together, and start trimming. This will work best with a strong helper.