http://orange.garmin.com/builtforblackberry/download.jsp
Click on that link in your Bold's browser and install it. Its about 1.5MB though.
There is a free trial period. 7 days if memory serves me right.
This is nearly as good as my Garmin Nuvi 650 windshield mounted unit.
Posted from my CrackBerry at wapforums.crackberry.com