Well Wayra,
It seems you have bigger problems then just to form an association! I'm sure you know that any association is only as strong as the solidarity of its membership.
I'm afraid I am ill equipped to assist you, what you appear to be fighting seems to be a cultural issue, I suspect that any written rules of conduct or SOP's might not have any impact on those who are still stuck in the last millenium.
Perhaps you will have to find other methods to "encourage" some of your (obviously) senior coleagues to get with the program.
Good luck!