Account Assignment Approval - Workflow

[RIVIERE Giselle EXIROS]

We want to implement the account assignment approval. We know that we
can use the WS00400032 (secuencial) or wS10000051 (PARALLEL).
Reading note 382670 we found out that there is a customer exit in order
to carry out the clerk determination for the account assignment approval.
 
We don't find any documentation telling us how to customize and to use
the subworkflow for account assignment approval. We won't use the
payment release workflow.
 
Any help will be appreciate.
 
Thanks for all, in advance
Giselle Riviere