Inside CV boots for 96 Infiniti I-30

My inside cv boots are split on my infiniti.....I do not know how long they have been this way.....they still have the grease in them....I do not know if that really matters....but I have a friend who wants to just change out the boots...how can you tell if any other parts have been damaged???How do you go about changing just the boots....Does anyone know or a sight I can go to find out?Please help.....