The list of pricebooks that should be active is saved in a system-level Site Preference called, SitePriceBooks. This value can be set by importing a preferences.xml file in a site import/export archive. The value of this site preference should be a colon (:) separated list of pricebook IDs. eg:
<preference preference-id="SitePriceBooks">list-prices:sale-prices</preference>The entire file should look like the following code snippet: