I think the fact that you end up with a very unidiomatic sentence shows the value of this sort of exercise (there isn't much).
The to is a preposition which you need to retain.
Tom is going to school.
*School is being gone to by Tom.
However going to cannot be passivised like this. Go is intransitive and it just doesn't work — that's probably why it's not mentioned in your reference.
You can turn a transitive verb like visit into a passive construction:
Tom is visiting the school.
The school is being visited by Tom.
Again, although it is grammatical, such a passive sentence would be used only rarely.