A parent can request an evaluation for a 504 plan. The purposes of the two things (Special Education vs 504) are actually quite different.
However, I went back and read a couple of your previous posts about your son. I didn't read everything - didn't have time - but what I read from your initial post and a couple since then suggests to me that there may be other explanations besides ADHD for your difficulties.
Please take whatever works for you and leave the rest because I could be completely off base. But I have a couple really smart (150+ IQ) kids who have learning issues and come from a family of really smart people and I think the previous poster may have hit the nail on the head.
If he is so smart he should be receiving challenging curriculum. Why should he make an effort to focus if it's too easy for him and it's boring?
Rather than push for a 504 plan, perhaps you should be pushing for a gifted program or at least more challenging material. Maybe he needs to jump a grade.
As for home, I am guessing he is not a compliant child and your other kids are. In that case you have no experience dealing with a kid who requires very firm limits but may need more flexibility at times because of his intellectual maturity.
You do not want to get a pattern established where he is challenging your authority and arguing with you at the tender age of 6 or 7. So you are going to have to adapt your parenting to cope with his special needs. Because kids who are really smart are special needs kids. They literally perceive the world differently and they need special help understanding this.
My suggestion is that you read the article at this link and see if it fits your experiences with your son:
http://www.sengifted.org/articles_counseling/Webb_MisdiagnosisAndDualDiagnosisOfGiftedChildren.shtml
If so, then that will give you a frame of reference for shifting the focus and style of your parenting of him and for you to address things at school.
You may want to take him for an independent evaluation of his intelligence before you approach the school about moving him to a gifted program. If his IQ is very high (150+) you may have trouble finding programs that are suitable at your local school district because this level of intelligence is very rare. In that case you will want to do some research into appropriate educational programs for him.
Good luck,
Patricia