I have figured out a very manual way of doing it using LeeMac's Point Manager. I copy of the Level/Offset for each chainage and paste them into a blank Excel sheet. Then I switch the column order to be Offset/Level. When I import the file using PTM it draws the cross section perfectly. Only problem is that I had to do them individually and move each cross section after drawing to avoid the next one coming in on top of it.
Could anyone suggest any ways to automate more of the process? Maybe even on the autocad side. Thanks.