This is a rough outline of the process for Working Group 1, leading up to the first public draft milestone:
For voting we will use a preferential voting mechanism, so that any number of proposals can be made without detracting from each other or forcing an all-or-nothing situation. The exact method remains to be decided, but will likely be either ranked pairs or Schultz. In addition, at least a minimum percentage, yet to be decided but likely in the 75-90% range, of voters must prefer the winning option to the R5RS (no-change) option.
A detailed example of the voting process can be found in the Yak Handler proposal.
The hope is that with this system and a more or less balanced representation of Scheme implementations and ideals among the members, we can ensure that while nothing crazy gets added, any feature that is almost universally desired _will_ get accepted, even if we can't agree on all the details.
Overall it's important that Working Group 1 err on the side of conservatism, to ensure a wider acceptance among implementations than R6RS received. It's harder to remove features than to add them, and we have Working Group 2 to add any extra features necessary.