Honestly, I woudn't bother. It sounds like you practice enough already (calloused fingers and blisters!) and the whole shredneck thing looks like a gimmick to me. I play about 2 hours per week (I have never practiced scales, I just practice by working out what I can hear in my head). There have been a few threads here where the more advanced guys have admitted to becoming better guitarists by actually playing less. It certainly worked for me.
My advice is to forget the shredneck and stock up on the cd's of great guitarists and just listen to them when you aren't practising. And by listening, I mean realy 'listening'. Most people don't actually hear the technique and skill behind a lot of guitarmanship. If you can hear it, understand it and can visualise it, it becomes a lot easier to play. I could never sweep pick untill I spent some time listing to Jason Becker, then I realised how he did it and was able to do it too (with a bit of practise!).
The shredneck looks like it will just get you into playing scales and you wont be able to hear if you are playing cleanly or not. Anyway, playing without any music is no fun!