In one aspect, a method for assembling a tower section of a lattice tower structure for a wind turbine on a tower assembly fixture may generally include installing a first trolley onto a first fixture arm of the fixture and installing a second trolley onto a second fixture arm of the fixture. In addition, the method may include securing a first support leg of the tower section to the first trolley, securing a second support leg of the tower section to the second trolley and coupling at least one secondary support member between the first and seconds support legs.