Installing fab 40 using a script, is one of the most popular posts here. However, this installation guide covered wsp only and not stp. So here is the scripted installation guide for site template files.
Copy all stp files in a folder – like – C:\SharePointTemplates. Create a batch file in the same folder. Type in this command
for %%f in (*.stp) do stsadm.exe -o addtemplate -filename %%f -title %%f
Save the batch file and run it!
You can download the script from my skydrive.