In reply to s krishnan.

This isn't a coding question, it is a statistical question, so I suggest you ask it on a statistical discussion forum such as CrossValidated. After you decide how you want to weight each observation, then put that value in a variable and use it on the WEIGHT statement. For example, if you decide to multiply the frequency, item weight, and importance weight together, then you would create
w = frequency * Item_weight * Weights_DuetoImportance;
Be warned, however, that you are essentially "inventing" a weight, so none of the inferential statistics (such as standard errors, degrees of freedom, and p-values) are going to be applicable.