Checkpoint crossing altitudes

Hello,I flew yesterday from KSFO to EHAM. Before going to bed I decided I would add to the FMC that I wanted to be at VALIE maintainign FL370. But it doesn't seem to be an option. I tried setting my ALT readout to FL370 and I tried inserting FL370 at waypoint VALIE in the FMC.But it does not accept this and gives me an invalid entry.Is there any way this can be done, or does a clearance of e.g. "Cleared to maintain FL370 at VALIE" a manual operation?Thanks,Xander