Found my customer CDs - I have two:

NEC Aspire System Document CD P/N 0893600 Rev 12
Feb 5, 2007
NEC Aspire Mail System Document CD P/N 0893605
April 4, 2006

The first CD does contain PCPro and the Aspire Mail Admin program along with CTI and USB drivers, as well as a wealth of documentation. If your customer can locate this CD you should be all set.