Seems there is no other way. You have to open all the ports of the firewall when you upload the app. The port shown here may not be consistent. 
Here is a snapshot of the communication,
(src ip -        dst ip -           protocol -  src_port > dst_port)
> 10.145.50.51  17.152.249.56       TCP         56358 > 33001
> 10.145.50.51  17.152.249.102      TCP         56373 > 44001 
> 10.145.50.51  17.152.19.127       TCP         56369 > https
System and Network Requirements
Application Loader 1.3 requires a minimum OS version of Mac OS X 10.5.3.
Note: Because Application Loader is integrated with Xcode you can also deliver your binary directly from
Xcode. For more information on this delivery mechanism, review the Distributing Applications section in the
iOS Development Guide located in the iOS Dev Center.
The following table lists details about the servers Application Loader uses to deliver your application binary
files to the App Store. For the best upload experience, verify that all of the ports and IP addresses are accessible.
The following table lists details about the servers Application Loader uses to deliver packages and application binary files. For the best upload experience, verify that all of the ports and IP addresses are accessible.
<Server                  IP Address       TCP Port   UDP Port>  
-------                  ----------       --------   ---------
itmsdav.apple.com       17.152.19.125    443        n/a
contentdelivery.itunes.apple.com 
                        17.152.19.127    443*       n/a
vgr101.apple.com        17.152.249.51    33001  33001-33500
vgr102.apple.com        17.152.249.52    33001  33001-33500
vgr103.apple.com        17.152.249.53    33001  33001-33500
vgr104.apple.com        17.152.249.54    33001  33001-33500
vgr105.apple.com        17.152.249.55    33001  33001-33500
vgr106.apple.com        17.152.249.56    33001  33001-33500
vgr107.apple.com        17.152.249.57    33001  33001-33500
vgr108.apple.com        17.152.249.58    33001  33001-33500
vgr301.apple.com        17.172.190.141   33001  33001-33500
vgr302.apple.com        17.172.190.142   33001  33001-33500
vgr303.apple.com        17.172.190.143   33001  33001-33500
vgr304.apple.com        17.172.190.144   33001  33001-33500
vgr305.apple.com        17.172.190.145   33001  33001-33500
vgr306.apple.com        17.172.190.146   33001  33001-33500
vgr307.apple.com        17.172.190.147   33001  33001-33500
vgr308.apple.com        17.172.190.148   33001  33001-33500
sgr201.apple.com        17.152.249.101   44001  44001-44500
Note: Because Apple periodically releases new versions and updates to its software, servers listed in the table may change mid-release.