There are two elements of what you're trying to adjust for:
1) The effect of the wind on the outbound leg itself. Just use the ratio of the windspeed to airspeed: e.g. if you're flying outbound at 120 kt with a 15 kt tailwind, reduce the timing by a little more than 10%.
2) The effect of the wind on the inbound turn. The turn takes about a minute. So use whatever proportion of a minute the airspeed proportion requires: if you're flying at 120 kt with a 15 kt outbound tailwind, 7 or 8 seconds (60*15/120).
So all in all, you take the outbound leg timing, add a minute, and use the wind to airspeed ratio. E.g. if you're flying at 120 kt with a 15 kt outbound tailwind with 4 min outbound, subtract 15/120ths of 5 minutes which is a shade over 30 seconds.
Notso's second per knot will tend to undercook the correction for typical ILS outbound legs, but since you're usually subtracting time for the outbound tailwind, it means you're usually going to end up a little further out with a little more time to intercept -- that's often no bad thing, as long as it's not taken to extremes.