you might be able to accomplish this using subreports and making the report multi column.
The subreport might allow you to control the size of a memo, and the multicolumn will let you print 2 side by side, but subreports tend to slow a report down.
Thinking about it a bit more, you might be able to use just gouping and multi column to get the 4 per page, but I would think that it would get tricky as if there are lots of items on 1 customer, it will quite possibly destroy the output you are looking for.
HTH