If employees have issues with you as a consultant, it is quite likely they have issues with their manager too.

I remember before I became a consultant the shock and anger I felt when, as an employee with a new project I was getting just my teeth into, a consultant was 'parachuted in' without involving me in the decision. As it turned out I quickly realised that I could learn lots from him and my resentment abated, but it could have been quite different. So I always make a point of talking early on to the people whose noses may have been put out to check with them what they think of my coming in. Sometimes I use the above experience as a way of getting into the conversation.

I also agree with reisen55 that if you have to call a meeting, bringing in cakes to go with the coffee goes a long way! Of course they see through the gesture, but it can be a source of humour and they do lift the mood!

Steve
http://www.opazity.com