Keyless entry,or even a remote start is possible,but there is a lot of wiring to install it correctly.A professional remote start installation can run as high as $400 if you want all the fancy features hooked up.
As long as the Central locking system works,you just need to tie the lock and unlock trigger wires into it for it to work.The remote starter gets a little more involved,and is not really recommended on a manual trans.