populating a table with unique ID and matching value

I am trying to set up traffic flow network with Excel Macro.
The first macro( in command tab) creates unique ID's for each traffic movement at an intersection with have start-node, mid-node, and end-node. if a particular movement starts at Int 1, pass through 2, and would eventually end up at 3, its node sequence ID would be 1S2M3E. For new trips generated by "A", a user will enter pathway for Auto In. if Auto In starts its trip at Int 1, and passes through 4, 2, and terminates at 6, we can determine all IDs that this pathway would use - 1S4M2E, and and 4S2M6E, Loop stops when nodes are fewer than 3.
1) how can I automatically create nodesequence ID’s for all used movements once the user enters the pathway intersection no.s and 2) how can I populate the table automatically with percent distribution for each pathway?

I am attaching the xls file that somewhat explains what I am trying to do.... the first tab"AM_Auto1_IN" shows the populated tables (in green) that would need to be created with macro.
Thanks!