Tramadol is an atypical opioid. Meaning it isn't a "typical" opiate like morphine or codeine, and is synthetically derived. Tramadol has a mixed action that isn't fully understood, but it is (at least partially) metabolized into o-desmethyltramadol which is what gives tramadol it's unique mu-agonist properties.
Abusing tramadol does come with risks, including seizures. It's never a smart idea to take more than 400mg in a 24hour period, as the 'threshold' for seizure territory can vary from person to person.
The seizure risk isn't taken seriously enough IMO, and it is a horrible experience. I would not wish it on my worst enemy. My advice to your husband (if he has a problem with abusing tramadol in extremely high dosages) is to start taking a small dosage of a benzodiazepine with the tramadol. When I say small, I mean minimal. The lowest possible dosage. You need very little to get the anti-convulsant effect you're after here.
The best way to take tramadol, plain and simply, is to "ramp" your dosage up. Dose in small intervals over a set period of time until you reach the desired dosage. A lot of the more unpleasant side effects (especially from high doses) can be reduced by doing this properly, as opposed to eating them all at once.
BuddingPharmacist: Please keep opinions and the like to a minimum, as they do nothing to add to the subject at hand.
EDIT: Do not smoke tramadol. Or any pills for that matter, ever.