I had attended a training workshop conducted by IBM @ Singapore and these were the exams they asked me to take inorder for me to become IBM Certified Trainer..
There were three paths - Step 1 -> WSAD, Step 2 -> WAS , Step 3 -> Portal
Learning Path for IBM Websphere and the exam Tests Required
Step 1: SW232 -> SW225 -> SW257 (SW237: Optional)
You need to clear Test 286 & 287 for becoming a IBM Certified Trainer.
Step 2: SW246
Step 3: SW553, SW543.(No professional certification is required !)