vesting title in SD 401k

[L George]

Hi, I'm trying to figure out the proper way to vest title for a purchase of real estate within my self-directed 401k. Unlike an SD IRA there is no custodian; I am the employer (sole proprietorship) and trustee. The title company (in California) says vesting must include trustee names, so I want to make very sure that my involvement is represented clearly as a trustee, with no personal benefit or gain.
I've found specific wording examples for IRA's, but - oddly? - not for 401k's. Any suggestions on where I might find something about this, or even what type of attorney to consult about it? Thanks -