Hi fratello,
Quote Originally Posted by fratello
Using PIC 16F628A I build this remote-by-wire for my Blaupunkt...
Did you change your mind? No IR anymore?

If I'm wrong and you still want to go for wireless, then you can improve a few points.
Quote Originally Posted by eggman
You should modulate your signal on a carrier of about 38 kHz...
Ignoring the use of a carrier frequency will make you very frustrated because of the very poor efficiency of your remote.

You can simply use the PWM module and PORTB.3 to do this; nothing else is necessary (not even assembly). The trick using PWM is to switch ON (set a value) and OFF (set to zero) the duty-cycle for the time of the HIGH and LOW pulses

OR have a look here if you want to make it another way (adding external components): http://www.rentron.com/Infrared_Communication.htm

According to you schema, you need to "switch ON" permanently your circuit to be able to use it. What if you forget to switch it OFF during a few days? You may need to add a "soft-switch". A soft-switch will combine your buttons as command and power-switch; a simple search will help you.