From outside the tools directory (obviously, you need to change to suit your path taste):
$ sudo /opt/android-sdk-macosx/tools/android
From within the tools directory (note the leading dot and slash):
$ cd /opt/android-sdk-macosx/tools/
$ sudo ./android
Related: you should have both ANDROID_SDK_ROOT and ANDROID_NDK_ROOT set in your environment. ANDROID_SDK_ROOT is used by the (now deprecated) ddms program. ANDROID_NDK_ROOT is used by various NDK tools. See Recommended NDK Directory? on the Android NDK user list.
