Is there a keyboard shortcut to open a mouse right click menu? For example use the tab key to select a link and use a keyboard shortcut to bring up the right click menu.

Read this thread:
http://kmeleonbrowser.org/forum/read.php?1,76254

Your solution is similar with this line, for example to use Ctrl+Alt+R:

CTRL ALT R = RButton

Please, you must read the documentation about accelerators:
http://kmeleon.sourceforge.net/wiki/ConfigFiles#accel

K-Meleon in Spanish

Intead a combination of keys... what about use the keys of the keyboard.

If you have enabled the option of search in the page while you type, that would help to locate your link. Then, with the key of the keyboard between the right CTRL and the Windows key, you can show up the right click menu.

Ah, that dang Windows menu key! Thanks!