Tough one. Part 61.65 requires that you receive 15 hours of instrument training. That goes some way to answering the issue BEagle raised -- I can't see any regulation that requires that the person giving the training is acting as pilot in command.
But didn't this one come up in another place recently, in that we decided that the 15 hours of training could be your IMC rating training, as long as it is properly signed off?