I am taking some baby steps in programming here. So if I am too close to the fire don't let me get burned.
I guess you are saying you can't add the layer to a new dataframe and change the dataframe to time enabled.
1. Can you open an existing mxd and update the workspace paths or datasources?
2. Then add the layer to the existing dataframe that is already time enabled. As with example 2 below and modify the time settings?
Maybe that is (implied by your non-pursuit) the solution you already had in your head.
This is not a real answer (you already accepted one).
Is it appropriate to follow-up an answer like this with further questions?
Quote from preceding esri link:
DataFrameTime example 2
The following script is identical to example 1 above but uses a modified start time, end time, and interval that are different from the existing settings that were published in a time-enabled data frame within a map document. The Python datetime module is used to create times and time deltas
import arcpy, datetime
mxd = arcpy.mapping.MapDocument(r"C:\Project\Project.mxd")
df = arcpy.mapping.ListDataFrames(mxd, "Traffic Analysis")
df.time.currentTime = datetime.datetime(2008, 10, 1)
endTime = datetime.datetime(2008, 10, 31)
interval = datetime.timedelta(days=7)
while df.time.currentTime <= endTime:
#An example str(newTime) would be: "2008-01-29 02:19:59"
#The following line splits the string at the space and takes the first
# item in the resulting string.
fileName = str(df.time.currentTime).split(" ") + ".png"
arcpy.mapping.ExportToPNG(mxd, r"C:\Project\Output\\" + fileName, df)
df.time.currentTime = df.time.currentTime + interval