According to FAR 117.23, the only time counted is that flown "by flightcrew members on behalf of any certificate holder or 91K Program Manager". As far as I know, there has never been an interpretation to expand certificate holder to anything beyond 121 or 91k operators. At my last airline, they asked for all commercial hours, but only recorded 121 and 91k hours for FAR 117 purposes. If you wanted to instruct on the side, you only need to inform the CP and have an acknowledgement from him. YMMV.