There are couple of coding examples provided in the Mobile Web Server Book available in http://mymobilesite.net/files/Mobile...er_Book_en.pdf . In the case you find those examples little bit too complicated for your taste (like me) you might try the following as a starting point.
Create a file called hello.psp that looks like this:
Create other file called ht.acl:
text = 'world'
Hello <%= text %>!
Copy those to folder psp under your htdocs. Access with address [yoursite].mymobilesite.net/psp/hello.psp and it should do the trick.
Allow from all
AddHandler mod_python .psp .psp_
There's not much real action and no access control either, but the purpose is to show that templating is not the only way to do psp.