I soaked mine in bourbon for a week or two, shaking up the jar and turning it a few times a day. I then poured off the old bourbon instead of infusing as I was worried the oak flavor would be over the top given I used fresh American White Oak that I cut and toasted myself. No infection/souring, and after four months on the oak in secondary I racked to a keg and have the cubes back soaking in bourbon. When I use them a second time I will pour the old bourbon in with cubes.
According to an old BYO I have the bourbon will penetrate and sanitize the oak as long as you never let the oak surfaces go dry. Wine, OTOH, is not high enough in alcohol and wine kegs are best left to strictly sour beers such as flanders reds.