Custom Load Balancing Router

Looking to have a router custom programmed or existing linux or similar install customized to accomplish this. Router must accept multiple broadband connections (8 maximum). Can run on any PC platform. Must take outgoing traffic that is split over multiple broadband connections (Example 4 dsl lines) and re-direct to a co-located server/router. The receiving router/server will then be connected to a larger 100mbps/100mbps internet connection and will combine the incoming bandwidth from the first router out to the internet via the single 100mbps connection and return it to the beginning router to be - repacked to the source computer of the internet request. The purpose of this is to created combined bandwidth from multiple dsl or cable internet lines. Examples four 6mbps/768k dsl lines would turn into one 24mbps/3mbps connection utilizing the data center bandwidth to combine the data the comes in via multiple streams. Thank you