The poem is not extant. It's known only by indirection, cited by Vacca and Statius but hardly a full text. Vacca does not appear to be online, and is himself quite shadowy, even his floruit is unknown (something like 6th-8th century, though): out of all his commentaries, some of which seem to have survived into the Middle Ages, only that one item, the Vita Lucani, remains today, and it's not so sure it's by him. But whoever wrote it, that's where to find the passage about Lucan's de Incendio, at any rate.
Statius of course is easier. The Latin is online at Latin Library