supposedly in /usr/bin
this is the entry for it on my menu, you could edit menu and add it with that info
/usr/bin/xterm -geometry 40x15 -title ImageMagick +sb -iconic -e /usr/bin/display
if you don't see it in the menu, you can reinstall it, it should create the menu entry again
to be honest, it is a really unfriendly image viewer, anything is better than it or perhaps i am missing the idea of its purpose