I'm planning on installing (same size) speakers myself into my sister's car- should be an easy affair since all I'm doing is taking out the old and putting in the new and rescrewing. Unless you're installing an amp or something, then it shouldn't be too hard imo. Although it might be a bit daunting to strip your car's doors/trim without damaging anything.
Btw how much are you looking at spending? Just looking at a Stratty catalogue on my desk, I'm personally thinking of spending around $150 or so on a deck, maybe upto $220 if there's something nice (I see a nice Pioneer one), and then putting in some $100 speakers or so in the front, and maybe spend another $70 or so on ptuting 6x9s in the back. I was originally going to go as cheap as possible, but the price difference between the basics and something decent, isn't that much IMO (deck-wise, cheapest deck is $94, then $128 for a Sanyo, then $138 for a Pioneer, and so on...), and the speakers- well, you don't want to cut corners there if you can spend just a little bit more than the cheapest (I think there are some $12/$19 speakers?)....