Kcmod is a graphical tool for setting file permissions. I wrote it after the 20th time I needed to look up the correct syntax for setuid'ing a file. It's intended as an educational tool for learning about file permissions and octal notation and as an aid if you forget chmod syntax.
INSTALLATION
./configure
make
su
make install
If Kchmod doesn't appear in the K menu (it should be "File permission tool" in the "Utilities" submenu), it's due to a known bug. Deleting your .kde directory and creating a new one fixes it. Hopefully the bug will be fixed by the time you read this.
Read INSTALL for more detail
USE
Open the file you want to modify. Change the permissions to what you want.
Read the help files for more detail.