How to generate Interest Accruals via TR_TRINTACU for Internal Bank Accounts

We have been reading the Peoplebooks but cannot find a clear explanation as to how to configure the Banks and Internal Bank Accounts so that we are able to generate the Interest calculation for our cash pool.

We have a simple cash pool structure at present where BU 1 owns the Treasury Bank and 3 other BUs own participating bank accounts. All 4 bank accounts exist as External Bank accounts and are in EUROs. We use the CPW to create BAX transfers and want to know how we should configure the Banks and Internal Banks, to create In-House Banking Interest Accrual and track the pooled balances. In addition we would like to know how the accounting for the Interest amounts will be generated. We will want to expand the setup to 4 cash pools EUR, GBP, USD