Packaging plasmids
We routinely use 3rd generation packaging (pMDLg/pRRE + pRSV-Rev), but LeGO vectors are compatible with any 2nd or 3rd generation HIV-1 derived packaging system. For example, I have tested psPAX2 2nd generation packaging with very comparable results. You can use the packaging system that you already have in your lab, if you want to. Packaging plasmids are available through Addgene as well:
http://www.addgene.org/lentiviral/packaging/