I'm confused. The stock buttons associated with the part number you provided are used with 14v light bulbs.
If you have purchased the LED "blade" lamp replacements, these have resistors built-in for the voltage specified by the part you purchased. If you got the 6v version, it will light at 5v, but won't be as bright.
It shouldn't be a problem if you hook them up backwards. It won't burn them out or anything, they just won't work until you get it right. Use one to figure out the correct orientation and then wire the rest the same way.
RandyT