You don't have to get all of the prereq stuff done with PADI before you start switching over to SSI. Any void in the prereqs could be fulfilled while doing them with your SSI shop.
Straight from the standards:
Prerequisites for the Dive Control Specialist course are:
Be at least 18 years old.
Logged at least 50 open water dives.
Provide own scuba equipment of leadership quality.
Be certified at least at the Dive Guide level or equivalent.
Have logged experience in Navigation, Night Diving, Deep Diving and Search and Recovery.
Complete a Diver Stress and Rescue course or equivalent.
Each Dive Control Specialist Candidate is required to maintain his own current SSI training materials.
Requirements for Dive Guide certification are:
Maintain proof of current training in CPR.
Maintain proof of current training in first aid.
Serve apprenticeship time and do practice guiding as listed in the course curriculum.
Complete a fitness and watermanship evaluation.
Logged a total of at least 50 open water dives.
Maintain proof of being competent in the emergency administration of oxygen. This shall include knowledge of the medical principles involved and practical use of an emergency oxygen unit
Each Dive Guide Candidate receiving an certification must have passed a Final Exam with a minimum passing score of 90%.
Prerequisites for the Dive Guide course are:
Be at least 18 years old.
Logged at least 40 open water dives.
Provide own scuba equipment of leadership quality.
Have a current medical exam for scuba diving not older than 1 year signed by a licensed medical practitioner.
Be certified at least at the Advanced Open Water Diver level or equivalent.
Have logged experience in Navigation, Night Diving, Deep Diving and Search and Recovery.
Have completed a Diver Stress and Rescue course or equivalent.
