That depends on whether the graphics card detects and enables the TV-out during VGA BIOS initialization. I know that ATI's do.
Also, unlike in the fully booted OS where you can select that, you need to make sure your card's default TV standard matches what your display unit expects - NTSC, PAL, SECAM, and all the variations of them. (Generally, if your stuff is from local shops, you'll be fine in that regard.)