Just an FYI... Slackware is not a supported Host (or Guest) OS.
I figured as much, but that's not the reason for this failure..
I did't say it was however it is not unusual to have issues installing on unsupported Hosts. You might actually find more help in the Slackware community then here as that tends to be the case with some unsupported OSes.
You should also use the parameter --ignore-errors and you won't have any of those issues. Nevertheless if you are not using Slackware-Current, I suggest you to use VMWare Player 5.0.1
Also you might like to add the following lines to your rc.local in order to run vmware services at boot time.
(USB Daemon is not started automatically, and this is the reason why the installer fails. However it can work like a charm if you start it manually)
Hope this help you out...
There is an URL to a Slackware Community on G+