Pixologic Zbrush is familiar to digital artists opposite to fans of typography it is unhandy and unpopular. Thus digital letters creation by package spheres is the right way forward to the 3D type. Ready models is possible to use as the regular *.obj files after standard export.
Put the whole toolset package to any suitable folder, than load all .ztl files via Tools (Load Tool). Now choosing any glyph connect the following: SubTool > Append. Change the skeleton and create polygon mesh if necessary via: Adaptive skin > Make adaptive Skin.
Paul Gaboury, 3D Product Development Manager (Pixologic, Makers of ZBrush)