Can't trigger lambda's on SQS FIFO

Your only option here is to poll the queue at certain intervals.

You can create a CloudWatch event trigger that invokes a lambda function (lets say every 10 minutes) which polls the queue and does the processing.

Update

This is now possible. SQS FIFO queues can now be specified as an event source to your Lambda Function.

https://aws.amazon.com/blogs/compute/new-for-aws-lambda-sqs-fifo-as-an-event-source/

For anyone that is interested AWS Now Supports Lambda Triggers from FIFO SQS as of yesterday. Thanks @JohnRotenstein for pointing that out.