Hi Matt,
As Eggs said Nobs Track dropping down to The Jamieson is seriously steep, and the last time I walked down it around 8 months ago it was also very eroded towards the bottom. Assuming that the almost metre deep erosion channels are still there I wouldn't go anywhere near it in a standard 4wd. If you are thinking of a there and back type walk then take Brocks Road to the Saddle below King Billy No.2, Mt Clear is doable as a day walk from there but any further along towards The Nobs would probably mean an overnight walk.
I haven't climbed up from the Macalister side so it could be possible, stay off Son of a *&%$#! Spur though as I've been reliably told that it's aptly named.
Mt Clear Track is a walking track nowadays.
I was up there a few months ago doing the AAWT, here's a link to the most relevant section for you :-
http://goinferalonedayatatime.blogspot. ... lpine.htmlCheers