You'll need to submit a VTAC application like you did in 2011 - applications are now open. This link has further information:
http://futurestudents.unimelb.edu.au/admissions/applications/ug-dom Since you would've done 2 years of law by the end of the year, you should be able to receive credit or advanced standing for some subjects. I would assume that all subjects would be credited as general breadth subjects. You can receive credit for 3 Level 1 breadth subjects and from memory you can receive credit for 5 Level 2 or 3 breadth subjects.
Because you're in your 4th semester of tertiary studies, they will not take into consideration your ATAR, but look more closely at your law grades and averages, work experience, circumstances, personal statement etc... From memory, you should be aiming for a minimum GPA of 6/7 to be competitive, and an average of say 75% upwards.
But overall, yes you can definitely commence a Biomedicine degree in 2014 - it's up to you whether you want to apply for credits and finish the degree in less time, or go in there and study for 3 years straight. Good luck and all the best, I hope you get in!!