Yes, you can do this but it is not a simple or quick process. The following article on TechRepublic <a href=”http://articles.techrepublic.com.com/5100-1035-1052940.html”>http://articles.techrepublic.com.com/5100-1035-1052940.html</a> and others like it should steer you in the right direction.
Essentially, you need two or more full Class-C IP subnet blocks, an ASN, two ISPs and a BGP capable router. You will want to make sure that the circuits from the ISPs are fully redundant in the building, down to the street and beyond. If this is not the case, then there is the possibility that a local outage can potentially impact both circuits, in which case, all of this money, time and effort will have been wasted.