going to the correct directory and then typing the command doesn't help, because "." (current directory) is not in your search path ($PATH). Typing the full pathname should help: /opt/vmware/vma/bin/vifptarget . That, or adding that directory to your $PATH:
export PATH=$PATH:/opt/vmware/vma/bin
PS vifptarget is still spewing errors when I run it on my 5.1u1 vMA