Communication methods should be established early in the process and explicitly detailed. Having an email address does not mean someone checks their email daily, or even weekly. Having a fax number does not mean that someone will receive a fax in a timely manner. One person missed a teleconference because they were waiting to be called and we faxed out a toll free call-in number. Scheduling issues are much more difficult in a multi-organization group.
Every representative has a different set of obligations and schedule conflicts.
The best recommendations are to start 2 to 3 months ahead of the desired date and be extremely flexible. Roles in a multi-organization task force are similar to any other. An important difference is that no one selected task force members with the thought of balancing these roles. You can share roles or alternate roles, but all roles should exist in the group. The leader role includes organizing and facilitating meetings, eliciting commitments, and monitoring performance.