I took a closer look at this, and because of the complex validation involved, I think the best solution (in Model Builder) is to embed the tool run inside the Calculate Value tool to embed the parameter into the tool call. I got the value table syntax figured out by running the tool and looking at the messages (and Copy As Python Snippet) in the Results window.
create_tin(r"%XSCutlines%", "%SE2%")
def create_tin(in_lines, fld):
out_tin = arcpy.CreateScratchName("xtin", "", "tin", arcpy.env.scratchFolder)
arcpy.CreateTin_3d(
out_tin,
arcpy.spatialReference(2277),
"{} {} Hard_Line <None>".format(in_feat, fld))
return out_tin