Down here in Illinois we have the Jim Haigh memorial dive day, at the haigh Quarry. The Family owned quarry has had this dive for 6 years now and will have another dive this year. The memorial dive benefits the Shedd Aquarium in Chicago and DAN. It is usually attended by 200-300 people. You need to have a cause/benificiary to attract divers, and lots of volunteers. The Haigh Memorial dive has contributions from individuals and local dive shops to raffle off.
Lots of work and lots of time and lots of volunteers are needed. You may get some help from your local dive shops, as far as word of mouth advertising, and some assistance from any shop that knew your friend.
Haigh Quarry -- The Place for scuba diving in Northern Illinois the phone # is there if you think this is something you rreally want to do. You may want to start out small then grow.
GOOD LUCK!
He had good friends.