nz1nz2, just follow the requirements for the "unclassified" status. Forget about 510(k), it has nothing to do with this.
For example according to 21 CFR 801.40(d)) states that a Class I device that bears a U.P.C. on its label and device packages is deemed to meet all UDI labeling requirements and that the U.P.C. will serve as the UDI required by §801.20. but i don't find any specific requierments for unclassified devices