The blog I need help with is blog.surveyanalytics.com.
I think that what you want to do is write your own shortcode and use it here at wp.com. If so, the answer will be no. I say this with 99+% confidence, since I cannot imagine a means of doing this without a huge risk to the integrity of the site and every blog on it. I have no qualms about your intentions, but there are some ill-intentioned people out there (and in here, probably).
This is just a basic part of the underlying technology of the web browser, and it’s required for sites like gmail, Yahoo!, and others to operate.
There are ways a site can avoid this problem (generally by constantly changing the login cookie data with EVERY response, and invalidating the old ones immediately), but they require more horsepower on the backend than the blogging sites are really able to provide, and there’s still usually a small window of opportunity.