1. I don't like him a hundred percent.
2. I like him in part (partly).
3. I don't like him at all.
(Does #1 mean #2 or #3?)
4. I dislike him a hundred percent.
5. I like him partly.
6. I don't like him at all.
(Does #4 mean #5 or #6? It is a little confusing in the use of 'don't like' and 'dislike'?)
Of 1, 2, and 3, #3 is the best sentence. #2 is "iffy" and #1 is not used. Simply saying "I don't like him" is all you need.
Again, of 4, 5, and 6, #6 is the best. The others are not used.