Hi,
it is possible to do it with code stage:
var grid = (GuiGridView)GetSession().FindById(elementId);
grid.SelectedRows = selectedRows;
2 inputs:
SelectedRows - indexd of selected row (starting from 0 I think)
elementId - Element Id of table
Maybe you'll need to play with formatting a bit, I just created some custom collection and it took system format (in your case it might be ""dd.MM.yyyy"" instead).