You can upload your images to a webserver and enter an image tag refering to that images into the editor using the code plugin (the "html"-button).
Update:
You need to create the base64 encoded string and call the following tinymce command:
Example: For your system you will need to fit the base64-encoded string into the variable my_image_base64_string.
var my_image_base64_string = 'R0lGODlhEAAOALMAAOazToeHh0tLS/7LZv/0jvb29t/f3//Ub//ge8WSLf/rhf/3kdbW1mxsbP//mf///yH5BAAAAAAALAAAAAAQAA4AAARe8L1Ekyky67QZ1hLnjM5UUde0ECwLJoExKcppV0aCcGCmTIHEIUEqjgaORCMxIC6e0CcguWw6aFjsVMkkIr7g77ZKPJjPZqIyd7sJAgVGoEGv2xsBxqNgYPj/gAwXEQA7';
tinymce.activeEditor.execCommand('insertHTML', false, '<img src="data:image/gif;base64,' + my_image_base64_string + '" width="16" height="14">');