I'm guessing that what you want to do is replicate the TI-83/84 "NormProbPlot" on the TI-89. This is found on the TI-83/84 series as the last of the plot modes in the statistics plots. It is used to compare a data set to a normal distribution.
Your best bet is found here: http://brownmath.com/ti83/nchk89.htm
