installpkg will install vector or slackware pkgs to your system. it will not handle tar.gz files, they are usually src tarball(uncompiled source).
most source tarballs can be installed by extracting the src:
tar xvf ivtv-utils-1.4.0.tar.gz
changing into the newly created dir:
configuring the source (if there is a congfigure script):
compiling the src:
and finally installing the software:
If you want to use the package manager to install/uninstall you will first have to make a package.
you can use sbbuilder to create the pkg like this:
then change into the ivtv-utils/src folder:
edit the ivtv-utils.SlackBuild if needed. (this source has no configure script so delete the lines before make that try to run it)
then run the script:
after it completes install the pkg:
Hope that Helps.
there are lots of different types of code out there so this will not work for all of them, but after you try a few you will get more familiar with how its done , and you can always ask for more specific help.