With your hardware as follows :
B:\ -> Your PC's Floppy
D:\ -> Your Harddrive
D:\DOSC\ -> An existing directory on your D:\ drive functioning as the C drive in DOSBox. If not existing then create it.
Just as an example

Do the folowing in DOSBox. Don't type the "X:>".
Z:> mount C:\ "D:\DOSC\"
Z:> mount A:\ "B:\" -t floppy
Z:> A:
A:> setup (or install, or any installation program on your disk numbered one)

When switching between disks press CTRL+F4.

Also, if your a complete noob to DOSBox then check out the giudes section in the VOGONS-DOSBox thread in this forum. Sometimes using a frontend like DBGL or D.O.G. helps out a lot.

Erik.

Hi

I am almost in the same situation, the only difference is, my PC floppy drive is dead.
Luckily I did images of my floppies a long time ago. (in fact they are just folders named disk1, disk2, ... that contains what came on every floppy)
Now, I tried to mount every folder as the a: drive and cycle through them with Ctrl F4 without any success.

Is there a way to do that ?