I'm still working on some training materials for those interested in regulatory writing. In the meantime, I came across this announcement of an audio conference titled, An Introduction to Regulatory Writing: Creating an Effective Message, that you might want to check out.
I have not listened to it and I don't know the speaker, so I can't provide any guarantees about the quality. If you do buy it, please let us know if it was any good.
Thanks for reading!