possible, but complicated if you need to spilt package files...
Here's a link on installing from another os. You can hook the hard drive in to your current computer and try the method mentioned here http://marc.herbert.free.fr/linux/win2linstall.html
or ther are still a few other ways, such as downloading a boot floppy that will allow a net install of the os you wish to use.
lastly, slackware does allow for a floppy install. JUst follow the directions for the question
"Is it possible to install this operating system without a floppy drive?"
on the slacxkware installation FAQ page given here
Good luck, if you need any more help, please feel free to ask