There's no provision that I know of for an employer to fund an IRA with pre-tax wages.  IMO the wages should be reported on the W-2 as taxable income (and subject to SS/MC taxes) and the deduction taken on the 1040 as an IRA contribution (remember the good ol' days when we could just say "on line 32").

Look at the year-end paystub and see if the math supports your conclusion that this was pre-tax, I'm not sure a W-2 by itself is going to tell you anything.

This seems to be the week for discussions about clients making up their own tax laws.  There was one yesterday about a client who "wanted to" defer tax on his land sale for two years.  And another one later in the day that I can't remember the details to but the client "wanted" to do something that had no support from actual tax laws.