Just an advice... WE have a 5 day a week person posting to about 20 forums. It takes about 6h/day to make anything out of it. You must be cautious not to spam or you get banned. The only way to succeed is to cautiously blend your content with other stuff. Only very niche forums where you reciprocate with banners or buy a space is safe from getting banned.
This is NOT about just posting, the person you hire must be clever and dedicated = ( expensive) or you going to get killed before you get going....