sorry for not summarizing for so long... It took time to figure out that the qt4 USE flag is necessary to have the executable "VirtualBox" installed. Pkg compiles smoothly and the exe presents me with a VMWare Workstation -like tool. Its all nice, albeit somewhat slow, and does what I need.
I'm not sure if the mentioned USE flag behavior is the expected or just an err, as I'm probably not an average user of VB. In my experience some GUI problems that troubled me with _old_ VMWW-s are not present in actual VB but the speedlessness raises other problems for otherwise slow GUIs running within the guest. I will possibly continue using VB. On the other hand, I will work to make VMWW run on my Gentoo box, although I don't want to stick to specific kernel and ? SW pkgs just beacuse VMWW needs them. Thanks for all the comments. Best regards, toma