Keyboard shortcut for jumping directly to a specific input method
One option would be to download changeInput and assign shortcuts to shell commands like changeInput U.S..

You could also use KeyRemap4MacBook:

&lt;?xml version="1.0"?&gt;
&lt;root&gt;
  &lt;vkchangeinputsourcedef&gt;
    &lt;name&gt;KeyCode::VK_CHANGE_INPUTSOURCE_HIRAGANA&lt;/name&gt;
    &lt;inputsourceid_equal&gt;com.apple.inputmethod.Kotoeri.Japanese&lt;/inputsourceid_equal&gt;
  &lt;/vkchangeinputsourcedef&gt;
  &lt;vkchangeinputsourcedef&gt;
    &lt;name&gt;KeyCode::VK_CHANGE_INPUTSOURCE_KATAKANA&lt;/name&gt;
    &lt;inputsourceid_equal&gt;com.apple.inputmethod.Kotoeri.Japanese.Katakana&lt;/inputsourceid_equal&gt;
  &lt;/vkchangeinputsourcedef&gt;
  &lt;item&gt;
    &lt;name&gt;change_inputsources&lt;/name&gt;
    &lt;identifier&gt;change_inputsources&lt;/identifier&gt;
    &lt;autogen&gt;__KeyToKey__ KeyCode::E, VK_CONTROL | VK_OPTION | VK_COMMAND | ModifierFlag::NONE, KeyCode::VK_CHANGE_INPUTSOURCE_ENGLISH&lt;/autogen&gt;
    &lt;autogen&gt;__KeyToKey__ KeyCode::H, VK_CONTROL | VK_OPTION | VK_COMMAND | ModifierFlag::NONE, KeyCode::VK_CHANGE_INPUTSOURCE_HIRAGANA&lt;/autogen&gt;
    &lt;autogen&gt;__KeyToKey__ KeyCode::K, VK_CONTROL | VK_OPTION | VK_COMMAND | ModifierFlag::NONE, KeyCode::VK_CHANGE_INPUTSOURCE_KATAKANA&lt;/autogen&gt;
  &lt;/item&gt;
&lt;/root&gt;


See the private.xml documentation.

VK_CHANGE_INPUTSOURCE_ENGLISH is defined in vkchangeinputsourcedef.xml. You can see the IDs of input sources from EventViewer.app. Without | ModifierFlag::NONE for example the first setting would also apply to control-option-shift-command-E. See the source for the key code values and predefined settings.