12.04 - Alternative to sudo add-apt-repository ppa:upubuntu-com/web

I found this steps to install SoapUI:

http://www.upubuntu.com/2012/04/how-...b-service.html

but I cannot connect because a proxy.

Traceback (most recent call last): File
"/usr/bin/add-apt-repository", line 125, in
ppa_info = get_ppa_info_from_lp(user, ppa_name) File "/usr/lib/python2.7/dist-packages/softwareproperties/ppa.py", line 80,
in get_ppa_info_from_lp
curl.perform() pycurl.error: (7, "couldn't connect to host")

I dont have problems with apt-get update, so is there any way to install SoapUI modifying sources.list?

Regards

Javi