OpenSSH Tunneling

I'm having difficulty setting up tunneling, and I was hoping someone might have some insight. My current setup works just fine if the starting computer is not located behind its own proxy. But I cannot get the connection to work from a corporate LAN, which will be necessary when I'm on premises and need to get out. I've been switching to Verizon wifi when I need various ports, but this is a bad solution due to speed.

So, I have OpenSSH setup on the computer in my home office. It's setup on port 443, and it uses my main login user and pass to accept connections. I have a .bat file that triggers the following command in PuTTy when I run it:

putty -D 8080 -P 443 -ssh xx.xxx.xxx.xxx

The connection works just fine. I can log in, see my computer structure list directories, manipulate files, etc. Wonderful.

I have a browser set up to connect using SOCKS5. Over my wifi (with no corporate firewall), this works great. When I check my IP at www.ipchicken.com (my personal fave), it gives me my home office IP, just like it should. However, when I switch to corporate LAN, the connection to my PC remains active, but I cannot tunnel out past that point. The corporate LAN is using ISA Server (WINP - 8080).

I've read a couple tutorials on how to get the corporate proxy to play nice with OpenSSH, but I can't seem to get it to work, no matter what I try. Is there something big I'm missing here? What more info can I post to help get me to the right answer?