@ BEagle.
You have to remeber that FCOMs are operator and regulatory authority specific and I suspect you have one of these rather than a generic FCOM - or I seriously hope so and this isn't Airbus policy!
In our operation, the alternate route is planned at the destination landing weight for actual met conditions for the company route to the alternate at cost index zero with eng anti ice on. We have planned and pre-loaded routes for all the nominated alternates and the flight plan defaults to the regular alternate. If a different one is planned, the route can be selected in the FMGS and reviewed to see if the fuel burn is correct.
The route plan on the paper flight plan to the alternate is assuming the standard missed approach from the runway with the shortest arrival arriving at the alternate using the runway also with the shortest arrival. The FMGC will plan the fuel with the actual track distances and the crew have the option of changing the alternate fuel if they see fit.