Sanei,
for the MNSQ confidence intervals normality is assumed because the degrees for freedom is (typically very)large. Under the null hypothesis of model fit the MNSQ has an expecation of 1 and a variance that is computed internally, but not actually printed by ConQuest 3.0. To obtain this number you could subtract the lower 95% CI value from one and divide by 1.96 to get the SE. The to get an alternative find the appropriate nornmal deviate (eg 1.645 for a 90% interval) multiply that by the CI obtained above and substract from 1.0 for lower bound and add to 1.0 for the upper bound.
OK?
Ray