How about showing the access key to the user in the title attribute?

Se_IDE_TestRunner_with_adding_access_keys.diff

Index: common/src/js/core/TestRunner.html
===================================================================
--- common/src/js/core/TestRunner.html	(revision 8354)
+++ common/src/js/core/TestRunner.html	(working copy)
@@ -88,16 +88,16 @@
 
                     <div id="imageButtonPanel">
                         <button type="button" id="runSuite" onClick="htmlTestRunner.startTestSuite();"
-                                title="Run All tests" accesskey="a">
+                                title="Run All tests [a]" accesskey="a">
                         </button>
                         <button type="button" id="runSeleniumTest" onClick="htmlTestRunner.runSingleTest();"
-                                title="Run the Selected test" accesskey="r">
+                                title="Run the Selected test [r]" accesskey="r">
                         </button>
                         <button type="button" id="pauseTest" disabled="disabled"
-                                title="Pause/Continue" accesskey="p" class="cssPauseTest">
+                                title="Pause/Continue [p]" accesskey="p" class="cssPauseTest">
                         </button>
                         <button type="button" id="stepTest" disabled="disabled"
-                                title="Step" accesskey="s">
+                                title="Step [s]" accesskey="s">
                         </button>
                     </div>