If, by "BCA", you mean BCAPL, it is prohibited by Rule 1-41, but most leagues modify the rule under the authority of Rule 1-41-5. Just depends on your local modifications.
If, by "BCA", you mean World Standardized Rules, coaching is not a foul under the rules of the game. In addition, limited coaching is specifically allowed under WPA Regulation 23, although the regulation puts some fuzzy limits on the nature of the assistance. Also, WPA Regulation 1 fuzzifies the entire body of regulations.
Buddy