[R] Straight-line fitting with errors in both coordinates

[Pan, Chongle]

Hi All,
I want to fit a straight line into a group of two-dimensional data points with 
errors in both x and y coordinates. I found there is an algorithm provided in 
"NUMERICAL RECIPES IN C" http://www.library.cornell.edu/nr/bookcpdf/c15-3.pdf

I'm wondering if there is a similar function for this implemented in R. And 
how can I change the objective function, from example, from sum of squared 
error to sum of absolute error?

Regards,
Chongle