I'm not sure if you're still looking, but I managed to get my tekkit 3.1.2 server upgraded to 1.4 following the instructions on http://caliblog.de/2012_08_08/sywt-add-computercraft-1-4-1-to-tekkit-3-1/. The files say it's for 1.41, but everything on the computers shows 1.4 (maybe since it was only bug fixes they left it registered as 1.4?) Hope this helps