I think that the most expedient way would be to calculate it by hand. The method would be to compute a weighted total of all the mean squares (variances before dividing by degrees of freedom). Each mean square would be weighted by the degrees of freedom for that mean square. The result would be divided by the sum of the degrees of freedom. In summary, you are computing a weighted average weighting each mean square by its degrees of freedom. You do this easily on an Excel Spreadsheet.
AVE for each construct can be obtained by sum of squares of completely standardized factor loadings divided by this sum plus total of error variances for indicators.
AVE for each construct can be obtained by sum of squares of completely standardized factor loadings divided by this sum plus total of error variances for indicators.
AVE for each construct can be obtained by sum of squares of completely standardized factor loadings divided by this sum plus total of error variances for indicators.