These instructions work quite well.
Note the fix offered by davepyro on line 47.
I also found an easier way to embed the script in step 2.
Simply past the code from that step at the bottom of you Contact Form 7 screen for the form you are using.
Then the script only gets loaded when that for is called instead of on every page of your site.
I also have never been able to get Contact Form 7 to take files larger than 10MB or so. But that is unrelated to this hack.