I found a technique to permanently increase intelligence using the absorb attribute spell in conjunction with spell stacking (on the Xbox).
Create several spells:
1: On touch:
Weakness Mag. 100%; 2 sec
Cmnd Creat. 25; 2 sec
2: On touch:
Weakness Mag. 100%; 2sec
Cmnd Creat. 25; 2 sec
3: On touch:
Fortify Intelligence 50; 2 sec
Weakness Mag. 100%; 2 sec
Cmnd. Creat. 25; 2 sec
4: On touch:
Absorb Int. 20; 20 sec
Cmnd. Creat 25; 2 sec
Purchase or make a long lasting summons spell.
Cast summons, then cast spells 1 and 2 on the summoned creature repeatedly (a la spell stacking). Then cast spell 3 and 4 on the summons (in that order). Your intelligence will skyrocket after the last spell is cast.
Spell 3 is necessary because summons do not have unlimited intelligence for absorbing.
Beginning with int of 115 I stacked spells 1 and 2 about 40 times, after finishing the ritual I had int. 1750 and magicka of 3600. After the spell wore off, the increased intelligence and magicka remained. I was unable to remove the effects after waiting for 3 days, nor did they show up in my active effects. I can only imagine how enormous these numbers can become for a master of restoration.
I attempted it again and again and it appears to be repeatable with this character.
I assume this will work with any attribute by using the appropriate absorb attribute spell in place of absorb int. This may also work for skills, but I do not currently have the spells to test it (no fortify skill spell yet).
Enjoy being a god.
EDIT: It seems that this "permanent" increase doesn't save. But, as I recall, it doesn't wear off after being repeatedly cast. So, it seems that this is something that can be done at the beginning of a game session if desired without having permanent effects on the save file. Further testing might be necessary.