Run SSIS Package as different user
Amusingly enough, you have the answer in your question, specifically, run as. RunAs and in case MS butchers links again, RunAs

RunAs allows you to run a program as another user. You can't automate the entry of credentials, which is a pain and you won't be able to see your password but it does work. It also fails in situations like SSRS development when you attempt to preview a report, that is spawned in a separate process which does not inherit the credentials. But, I had no issues with it from an SSIS perspective. 

runas /netonly /user:OtherDomain\billinkc "devenv.exe /nosplash"


where "devenv.exe" is the full qualified path to your Visual Studio version and whether you have a 64 bit OS. On my machine, that could be


C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\devenv.exe
C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\devenv.exe
C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\devenv.exe
C:\Program Files (x86)\Microsoft Visual Studio 9.0\Common7\IDE\devenv.exe