In the book I use the car package to get VIF and other multicollinearity diagnostics. I’ve occasionally found this breaks down (usually through mixing different versions of R on different machines at work home or on the move). I recently saw the mctest package and thought it would be useful to use that as a backup – and also because it offers a slightly different set of diagnostics.
If you’d like to try it out I’ve written a helper function that makes it easier apply directly to a linear model. You can find the function and a simple example here.