Au contraire. It accepts source and target.
So it does. Though arguably in this case specifying a source is probably redundant.
True, if they can extract all the files. It'd be easier to find a repository of them.
Turns out the program is expand, not extract; (extract is the program for the same purpose provided with windows).
With each disk, one could do this command with each floppy/disk contents, after setting up the basic DOS system on C: and copying EXPAND.EXE as well as getting a working setup for the CD-ROM drive with the driver and MSCDEX:
expand -r A:\*.??_ C:\DOS
We want a basic DOS setup with CD-ROM support. you can get this with the first disk, which you have successfully used. You will also need a CD-ROM driver. My personal favourite is OAKCDROM.SYS. You will need to run the sys command on the hard disk, create a DOS folder, and copy over MSCDEX.EXE and the CD-ROM driver (which is not on the disk, this will need to be acquired separately). You will also want to copy EXPAND.EXE to the DOS HD directory. CONFIG.SYS and autoexec.bat should be created on the HD looking like this:
CONFIG.SYS
DEVICE=C:\OAKCDROM.SYS /D:OAKCD
PATH=C:\DOS
autoexec.bat
MSCDEX /D:OAKCD
With a basic setup this ought to boot fine. You should then be able to run EXPAND on the contents of each disk. This means you could easily just throw the contents of disk 2 and 3 onto the same image as a subdirectory (eg. DISK1 and DISK2) since the volume label is only needed by the setup program and this is essentially a manual install.
Then you just expand the files in each directory in the CD-R:
EXPAND -r D:\*.??_ C:\DOS\
EXPAND -r D:\DISK1\*.??_ C:\DOS\
EXPAND -r D:\DISK2\*.??_ C:\DOS\
This will expand the compressed files, You might want to look through them for the uncompressed equivalents, (since a few files are not compressed) and copy those over manually. After which, you should have DOS installed.