My mother has died and left a house in NJ to my brother and I. We have
listed it for sale, but in the meantime, I would like to borrow a
third of my 1/2 of it's currently appraised value. The deed is in her
name. Can I do this as her beneficiary or should the deed be put in
both our names or does it not matter?  I am the executrix of her
estate as well.

First, read up on your duties of the executor of the will or consult
with an attorney.  Better to just wait until the property sells and
get your money then.
You don't "own" the house until the estate goes through probate.

Your bank will probably lend you the money based on your expectations. Just ask!

Just a personal opinion:  I think getting a lien on the property will
be a hassle, and it certainly will not help sell the house, since you
and the realtor will have to explain the whole matter to any potential
buyers.  Try to avoid the loan.
Regards, Myoarin

Oh Myoarin, Where do you live? Most houses have loans! Have you never
heard of mortgages? In any event, the Bank may not even want 'a lien'.
A Personal Guarantee? YES>