CD/MP3 Player Installation in Honda Accord 99

[paaji]

I have honda accord 99. It alrady have tape player and cd player together. but i bought new CD/Mp3 player which i want to install.
The question i have how i join the wires for ignition, constant, and Ground.
Cause if i unplug the old cd player that has it own wires that goes into tape player. How would i connect the wires for new cd/mp3 player to tape player or directly to wires that is coming from battery to tape player.

I can put tape and cd/mp3 player on same wires to get power and same for speakers. but my question is if i accidently turn on both of devices what will happen cause they are sharing the power and speakers.

OR let me other way of connecting cd/mp3 player with tape player
I want to keep tape player with cd/mp3 player if possible

Also old cd player has its own harness that goes to tape player it is not like rca out
thanks