What is the easiest way to use a SQL Server backup to retrieve just a few rows?
There is no way to restore either a single table or a few rows in SQL server without a third party product. If the table for which you are trying to retrieve few rows is in a separate file group you can restore only that filegroup (assuming you have Enterprise edition).

Else use a third party product like Quest Litespeed. I believe it has a feature that lets you to restore just a table from backup.

If your database is huge, use backup compression (available in SQL 2008 R2 standard and enterprise edition). Usually, a compressed backup takes less time to restore.