It’s not easy in 7.6 (which is why we wrote the Web Browser module for 7.7. 
)
Hopefully someone who has done this will chime in, but I’d be looking at system.net.httpGet() and system.net.httpPost(). You’d be on your own for parsing and displaying the page you get with httpGet() – not a trivial task, but at least there’s no Javascript in the page you linked to.
I know you want to make this look like it’s in Ignition, but you may want to look at system.net.openURL(), too.