How do I set up an asset to be fully deducted by Section 179 in my QBO? Do I show it as fully depreciated in the first year? Is there a note or form to set up in QBO?

The only "change" you make in QBO is your year end journal entry for depreciation. Instead of Debit Depreciation expense $340 and Ctefot Accumulsted Depreciation (half year convention for first and last year) you will Debit Deprdcistion $3400 and Crddit Accumulated Depreciation $3400. That's it. You do not adjust anything else. The asset remains on the books at 3400 but it's value has been reduced by Depreciation of 100%