If you've never done it I would suggest starting out low. I'm not a huge fan of the DXM high so to just get a nice relaxing buzz without getting sick I would drink 1/4 of that bottle. I'm 6'2" and 250 Lbs.
Seems to me that this has been pretty much answered so I'll draw the curtains on this one. Honestly I know shit all about DXM so if I'm mistaken then please PM me if you feel I've dropped the close too soon, but I know all of this stuff has been covered extensively in the B&D DXM Thread and believe the Erowid dosages are pretty much bang on. On which basis, tis last orders round here so closing time looms large.