Get Customer List ID For Specific Customer

[PCIPal]

You can query a customer in QuickBooks based on the customer name and obtain the LIST ID by doing the following:
PCQB_RqNew ( "CustomerQuery" )
PCQB_RqAddFieldWithValue( "FullName" ; CNTCT::FullName )

The ListID is returned in the response.
PCQB_RsOpenFirstRecord
PCQB_RsGetFirstFieldValue( "ListID" )

For a detailed list of all available or required fields in a CustomerQuery, please reference the OSR at:
https://developer-static.intuit.com/qbSDK-current/Common/newOSR/index.html. You may also want to refer to the Developer's Guide for navigational tips on how to properly use the OSR.