is it possible to force the seller to honor the contract?
In some situations, yes. The name of the claim in court is "specific performance." I would expect you need at least an hour consultation with an attorney familiar with this area of law to get a better idea of where you stand.
Do you do this type of work or can you refer someone? I would like to initially have a demand letter sent asking for seller to sell the property or reimburse all costs associated with closing this property plus maybe a little extra for lying on disclosures. I'm not sure how much leverage knowing he lied on disclosures gets us. Really, I'd just like to scare him into selling the property, maybe at a little better price for the hassle.