Kia Sedona Rear Heater Bypass

So I know this can be done but because of the amount of corrosion I will have to do it right where these pipes t-off in between the engine and the firewall. My question is: How do I get in there? Can I get to it from inside the cabin through the firewall? I can see the connections from underneath the car but I would need arms like Jar Jar Binks to get to it.

I assume you have the older Sedona (PRE 2006)… These vans are netorious for rotting out there rear coolent lines, dumping there coolent, and over heating the motor (usually blowing it up as the temp gauge will not work with no coolent)… I dont know how I would bypass it, but if you cant bypass just repalce the pipe. I think there maybe a recall on it.