What you mentioned is about how to run the multivariate GARCH models, right?
If you have the version 6 of EViews (beta version can't), it is easy to run the standard multivariate GARCH models (like BEKK).
However, if you don't have the official version or you want to run some specific models, my suggestion is to use EViews program to do it.
You can see the object "logl" or see the EViews built-in sample programs, which provide bivariate and trivariate GARCH models.