I didn't have power locks in my car, so I had to buy a power lock kit. I got a Protocol 4-door lock kit (PPCL4) from ebay for $40. If you lock/unlock either the passenger or driver door, the rest of the locks follow.
The keyless entry/alarm system I got was a K9 Eclipse system. I also got it off of ebay for $90. It has 2 2-way lcd remotes and also has a hands-free arming feature. Basically, you get within about 10-15 feet of the car and it unlocks itself. The hands-free feature was the selling point for me. The alarm also comes with a shock sensor, so if someone smacks your car, the alarm will sound.
As for the amount of time it took, keep in mind that this was my first car alarm/door lock install, so I was extra cautious not to break anything (a lot of good that did!

). It took about 5-6 hours over a couple days to get everything installed. Running the wires to the power door locks and mounting the actuators on the doors took the longest amount of time because you have to remove the door panels. Also, it helps to have some sort of wire fish when running the wire because there are a lot of tight spaces you have to navigate, particularly on the passenger's front door. Mounting the actuators also was a pain because the door panels don't have a lot space. My hands got pretty cut up doing that. Make sure when you mount the actuators that the wires don't get in the way of the windows when you roll them down.
Probably the easiest thing for me to do was to hook up the wires. This part took me about 15-30 minutes, and most of that time was probing wires for voltage. Speaking of which, make sure you have a voltmeter, because you will need it when figuring out which wires go with which leads from the alarm system. The only difficult part of the wiring was running the wire to the siren, through the firewall, just because it was another tight space.
Organizing the wires in a nice fashion wasn't too difficult, but there are a LOT of wires to organize. I used tons of zip ties and mounted everything to the steering column under the dash. Overall, I am satisfied with the end result. It was a good learning process and I managed to keep all of the wires out of site mainly by running them next to existing wires.
To summarize, I would say the most difficult portions of the install were those where I had limited space to work with. That's how I accidentally blew the fuse, and working in the doors with the doorlock actuators was kind of a pain. If you are comfortable taking the door panels off of your car and working with/tapping into the electrical system, you shouldn't have very many issues.
If you aren't comfortable working with the electric components, check out
the12volt.com Info for Installers for some basic tutorials.