The drivers are available on the KonicaMinolta Support Site.
But before you rush off and try using them, understand there were no updates to the Minolta drivers after OS X Tiger (10.4) and the driver may no longer be installable, or even work if installed, on a Mac that has Lion or later. The Minolta drivers are likely written for PPC Macs; and Apple discontinued support for PPC based software when Lion was released ... same on Mt. Lion and Mavericks.
If you are connecting the scanner via USB, check About This Mac > More Info > System Report > Hardware > USB and see if it shows your scanner is connected (your scanner has to be turned on, also). If it's not showing, there may be a hardware problem - could be the cable.
That said, have you tried using Vuescan? The Scan Elite 5400 and 5400 II are both supported and you might not need the original Minolta drivers. It's worth a try. If Vuescan works with your 5400 then the problem is in the Silverfast software.
Regarding Silverfast, since the drivers are included and the Silverfast list of suported scanners indicates it supports the 5400 on Mavericks, have you checked to see if there is a special installer for the scanner drivers? Sometimes it's separate from the application installer. You might also contact Lasersoft Support
