C'mon people... The atmosphere in this forum is getting more and more hostile in the last few months, and a lot of posts are not exactly helpful for beginners. I'm as much annoyed by "newbie posts" as anyone else, but we have to accept the readme is not the answer to every question, as it's not always 100% clear on every topic.
Anyways, back on topic. I've tried to install a game from floppy images some months ago, and i think switching with CTRL-F4 basically did work - the problem was that DOSBox was not reading the volume labels of the mounted images, if i recall correctly. Don't have the time to test that again, though.
The readme for 0.72 (Windows) talks explicitly about swapping CD-ROM images, not floppy images - it doesn't explicitly say that switching floppy images isn't possible, though. If you look at the readme, it seems quite obvious that switching floppy images should work as well. No matter whether switching floppies works or not - there's one important piece of info missing from the readme, and that's the lenght of the command line inside DOSBox, which is limited. If you want to use three or more images, and are stating the complete path to those, you run into that limit pretty fast (happened to me with Wing Commander III).
madcrow: do some searching on VOGONS, i think the topic has been covered in some posts. And/or just try it yourself - basically, you'd mount more than one image on the command line ("imgmount <image1> <image2> <image3>"), and then switch these with CTRL-F4 (you'll get some notification about the switching in the DOSBox console window). I'm not 100% sure about the correct imgmount syntax for floppy images, it could be neccessary to give additional params on the command line (see the DOSBox readme for details). You could also try to copy the image's contents to a single directory, mount that and install from there, this works for many games. Hope that helps a bit. Just play around with the command a bit, and report your findings here. I'm pretty sure you'll get additional help when you can ask specific questions, and/or give more detailed info (what you are trying to install, format of images, DOSBox version, host OS, etc.).