by itemized deductions i assume you mean job related expenses. the term itemized deduction usually refers to those reported on schedule A like medical expenses, taxes, interest not business related, charity.
you'll need to allocate your job related expenses between your W-2 work and your self employed work. there is no absolutely right way to do this. it could be based on time doing each, gross revenue or some other reasonable method. those expense allocated to your 1099 work go on schedule c along with the 1099 revenue. those allocated to your W-2 are no longer deductible.
