Customizing Key Binds for vim

I think you can do it with the following settings.
The first four lines are required to start rectangular selection with each arrow key.
The last four lines are required to select one character at a time with the arrow keys holding down Ctrl+Alt even after you start selecting.(However, Vim is already in selection mode, so you can select only the arrow key without pressing the modifier key.)

noremap<C-A-Right><C-v>Right>
noremap <C-A-Left><C-v><Left>
noremap <C-A-Up><C-v><Up>
noremap <C-A-Down><C-v><Down>
vnoremap <C-A-Right><Right>
vnoremap<C-A-Left><Left>
vnoremap <C-A-Up><Up>
vnoremap <C-A-Down><Down>