Per the rules written, you can't do it. After you install one type of console, it's impossible to install a better type later in the game.
When a developer was told about this (Lukas) he didn't immediately dismiss the rules "oversight," but rather said it's something they have to think about. Note: this would be a change from the original Netrunner,
So, heads up on this.
p.s. Yes, 99% of me is confident that FFG will rule this an oversight and maintain consistency with original Netrunner on this. However, I found it very interesting that Lukas didn't just say, "oh yeah, our bad, it's *obviously* intended to operate like the original," but had a more "wait and see what the council determines" approach. This at least means that if your players give you crap on this issue, they have a leg to stand on.
Though, technically, the game prohibits rezzing any card or using paid abilities when approaching already rezzed ice as well (timing diagram, page 33), yet this seems to have been readily admitted as an oversight,