I found an old paper describing the procedure but it uses unconventional reagents such as methanetetraboronic acid methyl ester whose access is not easy.
Check out Prof. Patrick Walsh's (Univ of Pennsylvania) research on 1,1-alkenylboronate esters published in JACS. Check for two papers, one on generation of 1,alkenyl-1,1-heterobimetallics by Hongmei Li and the other on its application, in which I am the first author (check my publication in JACS).
Also might be helpful to check out Prof. Gary Molander's research on trifluoroborates (Univ of Pennsylvania).