We are not but I am interested in learning the setup also.  ACH payments would save a lot of time.

We also are not yet doing this, but planning to implement it later this year...

Attached to this post is a "How to ... Guide" on Electronic Funds Transfers.  It includes a step-by-step description of the process you will need to set this up in Sage ERP X3.  Thanks for asking.

Instructions look like version 6... can this be setup in version 5?

I'm not familiar with version 5, but it seems as though you should be able to do so.