I don't know which specific message you are using, but according to the specification, the messages have a minimum rate of 0.8Hz. Unfortunately, BKool trainers do not send power data on a power meter profile, so I don't know how far you can come with this.
Relevent piece from the specification:
7.6 Pages 19-26: FE Specific Main Data Pages
Data pages 19 to 26 contain data that is specific to the type of FE. Only pages relevant to the FE type should be sent by any one type of FE, and none are required pages for transmission under the ANT+ FE profile. If an FE specific data page is transmitted by the FE, it shall be sent at a minimum rate of 0.8Hz (i.e. once every five messages).