I don't think it's possible. The game wants 16-color (actually 15) background pictures so it can re-color them (like the Memorial screen is recolored Soldiers screen & so on). However, I've tried to introduce as many of those background pics as feasible into the Pedia, in colored versions. I could even cram the rest in if I went with the "pinup" idea (collectible Pedia entries, not neccesarily girls, randomly found on the Data Disk in addition to current contents, with no technological value).
@Alex_D: Thanks for the screenshots! I'll fix the text to fit (although no important parts seems to be missing, thankfully).