To compile the plugins, first you need to install KKEdit ( obviously ).

To compile for gtk2 for the current user run:
./makeall
./makeall install

This will install ALL the plugins for the current user into ~/.KKEdit/plugins-gtk, to install individual plugins cd into the relevent folder and run:
make
make install.

To compile for gtk2 for the users run:
./makeall GLOBAL=1
sudo ./makeall install GLOBAL=1

This will install ALL the plugins for ALL users into PREFIX/share/KKEdit/plugins-gtk, to install individual plugins cd into the relevent folder and run:
make GLOBAL=1
sudo make install GLOBAL=1

To compile for gtk3 for the current user run:
./makeall GTKVERSION=3
./makeall install GTKVERSION=3

This will install ALL the plugins for the current user into ~/.KKEdit3/plugins-gtk, to install individual plugins cd into the relevent folder and run:
make GTKVERSION=3
make install GTKVERSION=3.

To compile for gtk3 for the users Run:
./makeall GLOBAL=1 GTKVERSION=3
sudo ./makeall install GLOBAL=1 GTKVERSION=3

This will install ALL the plugins ALL users into PREFIX/share/KKEdit3/plugins-gtk, to install individual plugins cd into the relevent folder and run:
make GLOBAL=1 GTKVERSION=3
sudo make install GLOBAL=1 GTKVERSION=3

PREFIX defaults to /usr, you can also used a staged install by setting DESTDIR as normal eg:
make GLOBAL=1 PREFIX=/opt install DESTDIR=/tmp/xxx

Certain plugins need extra dependencies eg the terminal pane needs vte for gtk2 and vte-2.91 for gtk3, you should consult your distros package manager and/or forums on how to install dependencies.