Anyone know how those permissions could have gotten messed up in the first place?
Most likely trying to install a redhat version with alien, whatever that is.
One of the things an installation program does is install directories and set their permissions as it is installing the program. Since redhat is somewhat different from Slackware it most likely set the permissions that would be used in redhat.
I never use redhat packages to install a program on my system. NEVER,NEVER,NEVER!!!
Anyway from now on when you get warnings and errors while trying to install an app on Slackware, instead of giving up, come here or search the web for answers so you can learn how to take care of your system. You were probably just missing some really simple dependancies and needed to install them so your app would build.
And most times you can ignore warnings.
Better luck next time.