Yes, of course. The VL install doesn't touch any partitions you don't specifically ask it to touch. Everything on my system was intact so all I had to do was edit /etc/lilo.conf and run lilo -v as root.
eMachines EL-1300G desktop, 1.6GHz AMD Athlon 2650e CPU, 4GB RAM, nVidia GeForce 6150 SE video
CentOS 6.5 (will try VL64-7.1 soon)
Toshiba Satellite A135-S4727, Intel Pentium T2080 / 1.73 GHz, 2GB RAM, Intel GMA 950
HP Mini 110 netbook, 1.6GHz Intel Atom CPU, 2GB RAM, Intel 950 video, VL 7.1