Highlighting gridview row on mouseover - highlighting specific sections of the selected row

There are a number of articles on highlighting gridview rows, but how do I split the highlight function down the middle of the gridview to create a split highlight function ?

ie:- (a) the left hand fields in the selected row are only highlighted when there is a mouseover on any one of the left hand cells and (b) the right hand fields are only highlighted (in a different color to the lefthand highlights) when there is a mouseover on any one of the right hand cells.

Eg : A gridview returns six fields with results in three rows as follows:-

A1 B1 C1 D1 E1 F1
A2 B2 C2 D2 E2 F2
A3 B3 C3 D3 E3 F3


On mouseover on B2: A2,B2,C2 are all highlighted - ie the left hand side of row 2
On mouseover on F3: D3,E3, F3 are all highlighted - ie the right hand side of row 2
etc etc...

For reference there will always be an even number of fields in the gridview so the lefthand side and righthand side will always have an equal number of fields.