Open the file userh3.dat where userh3 is your userh3 which is found in the Characters DIR with a hex editor. Then modify any of the following offsets:
1D Body Points
3D Number of Spells
You can change skills but they must be there first. In game distribute 1 point for each skill then edit them in the file. Skill offsets start from A2 then AA B2 .... in 8 byte records.
Safe value for character stats is 100 this is enough for start and about 150 for skills.