I was thinking of installing an alpine IVA-W205 has anyone run into any problems that I should know about?

Getting the PAC TR-7 work to Bypass the E-Brake and Steering wheel controls.

dont bother wasting your money on the bypass...its a waste you can just wire one up to a switch yourself

^^^ True, but the TR-7 is much more convinient.

Yeah the Alpine bypass isn't just an ebrake type switch. It's a toe tapping "dance" between the brake and ebrake.

^the TR-7 doesnt require a tap dance in order to view DVD's on the w-200/205.... as soon as you select DVD as your source the TR-7 triggers the W-200/205 to think that you have the foot brake engaged therefor the video is displayed on the screen... very easy to wire and program... just make sure you have a good ground....

My post was a little vague, sorry. That's the point I was trying to make. It's not a simple bypass switch like you can do for the Nav. The TR-7 is definitely worth the money.

It it possible to install the TR-7 after I have installed the headunit without taking the headunit back out?

Only if you have access to all of the wires, which you probably don't.