Can you load share between two unequal cost paths (T1, T3) from RouterA to RouterB using eBGP? Any sample configs or technotes would be appreciated.
Yes you can.
The bgp path selection algorithm considers 2 or more paths equal when the following path attribues are equal:
If multiple paths have the same attributes above, then you should configure the "maximum-paths x" command under the bgp process.
This will cause the router to use multiple paths within the routing table, and will load share among the paths, but BGP will still advertise the best path only to its neighbors.