Planet Map makes textures that don't pinch at poles !!
online (fun, limited size, few tools) http://topps.diku.dk/torbenm/maps.msp
exe (has command line, many tools) http://hjemmesider.diku.dk/~torbenm/Planet/
if you generate map as 'square projection' with width twice height, the equirectangular map will nicely wrap a sphere without pinching at the poles...
Couple of gotchas:
fun on-line version limited to 1000x1000, so eg 800x400
You must 'save-as' its image, which only exports as BMP. So, you may have to open that in editor of your choice, re-save as much more compact JPG.
I've not tried the command-line {Shudder !!} version, but one option seems to be 'save as height map'.
As Poser could *perhaps* use such as Bump / Displacement map to enhance render of twinned texture map, I'll investigate when my hay-fever eases...,