Yeah, you need legal advice. The 401k issue will require some legal research and a tax opinion. You may need both a CPA and a lawyer. My partner does complex business acquisitions, but we do not quote prices online. It would not be prudent to quote a price before we saw exactly what you are looking to be done. Depending on the nature of your business, this could be a lot of work.
A primary issue is whether you're using a 401(k) account from a job you no longer have vs. one for an employer with whom you are currently associated. Plan documents generally govern what you can do with the money. If it's a 401(k) from a former employer, you can roll the assets into an IRA. Whether you can fund your venture through those IRA assets without incurring tax liabilities and other issues will require counsel.
The foregoing is not legal advice nor is it in any manner whatsoever meant to create or impute an attorney/client relationship.
Additionally, there are tax limits on using protected retirement funds to acquire an asset in which you will be actively involved. This is probably going to take advice from a CPA or tax attorney, as well as your business attorney.
And if you really use a "self-inflicted" LLC, you are likely to be creating a toxic situation which an attorney will not want to touch, or at the least, it will probably cost more than if he had been involved from the start.
If you really can't afford to have an attorney involved from the start for things that are this important, you are at the definition of "undercapitalized."