There was a post about this some time back...this is what i picked up , quite useful:
A basic group can be set up using this command:
GHGRI:GRP=xxxx,TRAF=15,QUE=yy,SERV=10000,SEL=110000;
xxxx is the number you wish to use, this must be a free number in the extension range.
yy is the queue...