Question:

Even though one can consciously relax the outer anal sphincter, is it its still necessary to “force” your way through the inner before the resulting stimulation of the rectum will cause it to relax? It just seems like a Catch-22 that you cannot elicit the desired unconditioned reflex without fighting the natural clench and the resulting pain.

Answer:

Most people do see this as a catch-22. The overwhelming public opinion is something like – Anal sex is always painful in the beginning but it gets easier
Even this statement has two interpretations and no one ever seems to make the distinction.
First point: just pushing past the pain will cause the Outer Anal Sphincter (OAS) as well as other related pelvic muscles to clench (fight or flight response). Pressing on regardless, the body releases endorphins to alleviate the pain, the fight or flight response subsides allowing the muscles to relax, the OAS and other muscles fatigue in addition to the stimulation of the rectal walls causing the Inner Anal Sphincter (IAS) to relax. This is the overwhelmingly common experience for anal beginners.
As long as the bottom is not put off by this experience and continues to accept anal penetration on a regular (weekly or at least a few times a month) then the classical conditioning kicks in and they get to the point were they only need a little bit of spit for lubricant to get things started.
At this point I feel it is appropriate to provide a link to another article – Compare anal with vaginal sex.

The better solution:

There are three primary sources of pain to deal with when initially penetrating the anus. The first is skin friction. Obvious. The solution is to use a good anal lubricant. Also obvious, and the place everyone starts and often stop. The second is muscle strains. The third is starting with something that is simple too fat and is going to over stretch the skin and/or muscles.
The process is to avoid straining the IAS with the first penetration. Basically, the first thing in the anus has to be thin enough not to strain the clenched IAS. Part of this consideration is that the anal canal is surrounded by multiple rings of muscle. Most tops make the mistake of thinking they are home free once they get passed the subcutaneous anal sphincter. This is the lowest ring of the OUTER anal sphincter. On some bottoms there is a noticeable gap between the Subcutaneous OAS and the IAS. If you push the tip of your finger (or anything else) into this gap you will trigger the pain response. But if you do it right, you can slip a well lubed finger through the entire length of the anal canal without causing any pain. Then you can trigger the release of the IAS by gently hooking the tip of your finger over the top of the anal canal and pulling on the bottom of the rectum. This is the starting point for Training an Anal Virgin
The process of avoiding over stretching the skin and anal canal generally is warm up and stretch training. Work you way up slowly over time and repeated penetrations – Staying in anal shape