Not really, FR is a painful tool to use......
What you may want to do is : 1.) Create report in FR, 2.) add a row using the member selector, select 1 row. 3.) Save the report, 4.) Export report (.DES) file, 5.) Look at the format of the file, it's an XML file. 6.) Create a script to create all of the rows you need for the accounts.
I've done something like this a couple of times, but it's not pleasant.
Like Erich said, you could create a member list and just pull the member list as one line item in your FR report. You can based the member list on a userdefined flag or several other criteria.
You can also create a member list by adding the specific accounts into an array if you would like to take a more manual approach (although this would be nearly as tedious as inserting the 400 lines into FR Studio).