Physically installing it shouldn't take too long at all. Actually getting it to run, however, may complicate things. First, you need to make sure every seal actually seals properly, then hope everything is compatible with R134a unless you have access to the old R12 or the R12 compatible new stuff. If you are lucky, it shouldn't be too bad. If you are not, you will have an AC that is nice for a couple weeks, max. My grandparents had an '86 Accord that just plain would not hold a coolant charge no matter how many times it went in to be fixed, while my old integra never had a problem (until I crashed it and destroyed the lines up front). My personal cost/benifit analysis of the situation would tell me to not bother, but I am sure a few guys on the board would disagree.