Or you could simply do:

*Hotkey CTRL G !ParseEvars !command ?google %[clipboardText]%

Only requires xlabel and lsxcommand be loaded.

1. Copy to clipboard. (ctrl + c)
2. Press hotkey. (ctrl + g)

edit -

Is there a Litestep module that will send key presses? I thought there was one, but I can't find it. With that, you could just have the hotkey line !execute the copy/!command, making the above just one step. I can't see a way without using an external program.