As far as I know
1) you can try using URL hacking technique and pass the Search value (if only you are using a custom visual force page, if not you enter into sidebar hacking techniques which partially is supported through links) even this approach may fail with some browsers when the length of the URL exceeds 2000 (some big random number) chars.
2) We have implemented a technique in our org that has been accepted by our users.
You need to make sure you restrict the data that is getting display in the lookup window through lookup filters, you do not want the user to sit for a while (or) scroll through 100's of records ( not sure about the limit / number of records you can display on the lookup window though)
Step 1: Create a dummy read only field on account and call it "All"
Step 2: Use data loader ( if you have a lot of records in your org) or use multiselect option ( I had only 30 records to update) and update the value of the newly created All field to "All"
Step3: On your lookup window text ( this is the actual name under lookup filter settings on any custom lookup field) type something like
1) Type "All" in the search box.
2) Choose "All Fields" from the Search options and click "Go".
This should give you all the records matching your filter criteria in your lookup window,
Finally show some love for this idea: https://success.salesforce.com/ideaView?id=08730000000kxgoAAA