Your requirement
You use xterm as a terminal emulation. This provides a menu for selecting fonts by pressing [Ctrl]-[right mouse button]. You want to change this menu and store your own fonts.
The Procedure
The configuration of xterm is done either in ~/.Xdefaults, or system-wide in /usr/X11/lib/X11/app-defaults/XTerm. The following lines create a separate font menu. The number of entries is set to 7.
~/.Xdefaults:*fontMenu.Label: Schritfart
*fontMenu*fontdefault*Label: Standard
*VT100*font: -misc-fixed-medium-r-semicondensed-*-13-120-75-75-c-60-iso10646-1
*VT100*wideFont: -misc-fixed-medium-r-normal-*-13-120-75-75-c-120-iso10646-1
*fontMenu*font1*Label: Fitzelig
*VT100*font1: -misc-nil-medium-r-*-*-2-*-*-*-*-*-*-*
*fontMenu*font2*Label: Mittel
*VT100*font2: -misc-fixed-medium-r-*-*-12-*-*-*-*-*-*-*
*fontMenu*font3*Label: 15'er
*VT100*font3: -misc-fixed-medium-r-*-*-15-*-*-*-*-*-*-*
*fontMenu*font4*Label: 20'er
*VT100*font4: -misc-fixed-medium-r-*-*-20-*-*-*-*-*-*-*
*fontMenu*font5*Label: 24'er
*VT100*font5: -*-fixed-medium-r-*-*-24-*-*-*-*-*-*-*
*fontMenu*font6*Label: 40'er
*VT100*font6: -etl-fixed-medium-r-*-*-40-*-*-*-*-*-*-*
What are my fonts called?
To find out which X11 fonts are available, you can use the xfontsel program. Click on a font together, then click on the Select button. The font’s name is now saved on the X11 clipboard. You can then insert the font into a text editor with the middle mouse button.