The HELOC interest can usually be deducted, as long as it is a secured loan (that is, your house is collateral and its recorded as a 2nd mortgage). But since you did not take the loan to buy, build, or improve you home there are a few limits to be aware of:
The amount of the loan can not exceed $100,000.
The amount of the loan can not exceed the fair market value of the house minus the first mortgage loan amount.
Interest on the portion of a loan above these limits can not be taken as a personal deduction. However, since the loan is for your business, you can treat it as a business expense on Schedule C.
See Pub 936 for lots of details:
Publication 936 (2007), Home Mortgage Interest Deduction