It is not necessary to center your variables when using the XWITH command. You should not mention the covariance between the two variables that are part of the interaction. Because these are covariates, the model is estimated conditioned on these variables. Their covariance is not estimated as part of the model. If you want to know the value, you can obtain it using TYPE=BASIC;.
Hi there. I am conducting an analysis where I model an interaction between two latent continuous variables (A and B) in the prediction of an observed continuous variable. I noticed that I am unable to specify a correlation between the main effects and the interaction (e.g., A with interaction and B with interaction). Is there someway that I can find out what the correlation would be. I appreciate any help that you can provide. Thanks.