Dude, corner node is hardly a "pointlessly academic term". What else would you call it?
Anyways, if you want slanted guidelines, simply pull a guide down, select it and set the desired angle in Design Central.
I understand that you're having problems making the transition to Flexi. All softwares (Corel, Omega, Illy etc) use their own terminology and commands to achieve the same basic results. Flexi is no different. After you spend some time learning and familiarizing yourself with Flexi and its commands, you'll be pleased with its capabilities.