so, do you need change tempdb database to a different folder or rename the existing folder??
if it just renaming, which it sounds like ... just alter the database settings and stop the sql server--rename the folder and start the sql server. something like this
USE [MASTER]
GO
Alter database TempDB
MODIFY File (Name= 'TempDev', FileName = 'E:\TempDBData\TempDev.mdf',SIZE = 4096MB , FILEGROW =500MB)
GO
Alter database TempDB
MODIFY File (Name= 'TempLog', FileName = 'E:\TempDBLog\TempLog.ldf',SIZE = 1024MB , FILEGROW =250MB)
it should be same for model and msdb. but if master after stopping and renaming the folders.. in the configuration manager -- properties-- in the file path - you need to specify the new path or changed path.