Uhm, nice question. Some hacking is required.
- Use pretty-permalinks on company site
- On the domain of the founder, do a URL-rewrite from http://www.founder-domain1.com to http://www.companysite.com/page-founder1
- On the company site, use a custom menu with a custom URL: Founder Page -> http://www.founder-domain1.com. (If you cannot use a custom menu, create a link in your template)
Of course, page-founder1 is the slug for the founder1 page that is edited via WordPress.
Substitute the domains as your needs.
Note:
Beware that you ARE depending on the slugs of the pages of the founders. If you change the slug, you must change the URL rewrite on the founders site.