We have now added the ability to post shares to LinkedIn Company Pages, in addition to the existing ability to post shares to LinkedIn profiles and LinkedIn Groups.
The feature is available to Professional users. To post shares to a LinkedIn company page, first add your LinkedIn profile as a social account with Social Accounts, Add New Account, Add LinkedIn in the menu. You will then be presented with a list of company pages that LinkedIn allows you to post shares to, and you can add those to your list of social accounts. If you have already added your LinkedIn profile, select Social Accounts, Manage Accounts in the menu and then click the Edit link of your LinkedIn profile account. You will then see the same list of company pages that you can add as social accounts.