Use the Fit Y by X platform. Specify your response and x variable.
Then on the red-traingle menu, select Compare Means > Each Pair, Student's t to do a t test of each pair. Select Compare Means > All Pairs, Tukey HSD to do a Tukey test on each pair. The t values and q values are part of the output. Remember, the t test doesn't correct for multiple comparisons, the Tukey test does. JMP has other multiple comparison procedures on that same menu. JMP 9 has all that plus nonparametric multiple comparisons.
Now that I read your post again, you may be asking about something else. If you are looking for JMP functions that will return quantiles or probabilties, then consider the following functions:
t distribution t quantile Tukey HSD Quantile Tukey HSD P Value