35 USC 301, which is cited by MPEP 2202 and 2204, does indeed only apply to issued patents (note that (a)(1) and (a)(2) stated "a particular patent
"). 35 USC 122(e), which is discussed in MPEP 1134 and 1134.01, is applicable to third-party submissions for patent applications.
This board has discussed how best to throw a monkey wrench into the prosecution of a competitor's patent applications a few times in the past:http://www.intelproplaw.com/ip_forum/index.php?topic=25788.0http://www.intelproplaw.com/ip_forum/index.php?topic=24788.15
I think the general consensus is that a third-party submission is a pretty bad idea because it does not guarantee that the examiner will actually read the references and consider them carefully. Also, your ability to explain why the references are relevant is pretty limited. Even further, the examiner will check off your third-party submission as considered, making it will look to outsiders like the examiner took the references seriously, even if the examiner did not actually do so. Some individuals have suggested that this could effectively create a higher burden to convince DCs as to your position than if you had never submitted the references to begin with ("Why are you arguing that the patent is invalid in light of these references? The patent office already considered these! SJ denied."). But if you have passed the time period for 122(e), that is irrelevant.
Sending the references to the competitor's counsel to try and force them to submit the references themselves under 37 CFR 1.56 is pretty interesting, but it still requires a lot of if's to be successful -- the counsel has to recognize that the references are material, the counsel has to be ethical, etc. Unless your goal is specifically to potentially hit them with an IEQ charge later, sending it to the opposing counsel will likewise not guarantee that the patent does not issue.
Therefore, IMO, the best way to assert your prior art is to allow the patent application to issue, then file an ex parte reexam, PGR, or IPR with the art. Which one to choose depends on your client's goals and timing.