How hard is it to replace piston rings?
 

I just recently got my drivers licence and got ownership to my dads 93
sonata v6. It eats oil, smokes, and its not very peppy; the mechanic
my dad always brings it to said it was the rings and it would cost $600
for him to replace them. I, now the owner of this car, think paying
600 for this is crazy and would like to attempt this myself. I have
had experience with small engines, in fact my 78 skidoo needed a ring
job, and I pulled that off without any problem. If I followed the
manual step by step, is there anything that would be overwhelming that
would justify paying the 600 dollars? And speaking of manuals, should
I buy a repair manual like the Chilton one or is the hma one online
sufficient? And are there any 100% necessary "special tools" needed
for this job?