First example is long.. second is non standard...
If you ABSOLUTELY must...
Look at jQUERY "pulsate"
I would prefer:
$("#element").fadeTo('slow', 0.5).fadeTo('slow', 1.0);
This would fade an element to 50% and then back - plus you could to this in a loop maybe 5-10 times so it's much less intrusive to the user.