In order to make a @DBLookup on the Web with more than 64k data, just copy the view ($PeopleGroupsFlat) from the public addressbook and use the (wAddress)-form from the mail db to do lookups on your data.
1.) Copy the view ($PeopleGroupsFlat) to your db. You can change the form selection and the displayed values in the columns for your needs but do not rename the view and change the number of columns.
2.) In the form (wAddress) set the value of the field NABs to your database location.
Although many people use this procedure for looking up names from NABs in different ways it works great for selecting a value from large amount of data of any kind. I use it to select imported data from SAP.
P.S. The Use of the DBCommand would be much easier if there would be a documentation from IRIS.