There's one issue that hasn't really been addressed so far, which is what the timing in the hold is intended to achieve. The US way, as mattpilot describes, is to adjust the outbound leg so that the inbound leg is 1 min long. The ICAO PANS-OPS way is simply a 1 min outbound "adjusted for wind". I've always interpreted that as half the correction that the US uses. In reality, as others have suggested, nobody cares.
To answer Hansard's original question, your groundspeed along the outbound leg is airspeed * cos(30 deg) or airspeed/1.15. Therefore to get a still-air minute of distance, add 15% or about 10 seconds.