Sales group wise authorization for sales order

Hi Gurus,

I need urgent help from you.

I am explaining my scenario :

I have defined customer group as sales region like west, east, north and south.

Now when i am creating sales order for say in north group i should get north group customers only in my match code search and i should create sales order with north sales group customer not with south or west sales group customer and also apart from north group customer other group customers should not be displayed in search.

I have explained this to my basis guy for giving authorization but he is failed to give authorization at this level. So can any body tell me how to do. So that i can explain to my basis guy.

Pls matter is very urgent since we are having go live next month 1st week.

advance thanks to all

i will reward for good suggestions.

regards

Sree