Not particularly easily, but it's possible. You have two choices:
1) Install RPM - this used to be included with Slackware, but I haven't looked lately. Then you can use RPM directly. However, since you don't have an RPM database full of packages, every package will complain about missing dependencies, so you'll need to install with the "--nodeps" option.
2) Convert the package to .tgz format. Slackware has a tool called "rpm2tgz" that converts binary RPM's to .tgz packages. I had some trouble when I tried to use it, but it may work for you. I think that Alien can do this, too, but it may depend on RPM itself being installed.