Markschum is right.

Everytime model around the original zero posed figure. As best you load it directly from the geometries. You need not to export from poser and therefor avoid some trouble with that.

All what is modeled around that original figure will (most) easily be rigged with a donor from orginal figure or similar clothing/shoes. You need not split the mesh between foot and toe. But toe-actor is needed in cr2 to move the toes even if they are part of the foot geometry. You may have a look to one of my models at shareCG.

The only point been tricky while modeling in that pose is to define correct bending area for toe and the correct length and angle of a heel. It's best done (for me) finding the break between toe and foot in the mesh and have a square plane with the rotation axis in that break line. Now you may vary the horizontal angle of that plane to have a new dummy floor depending how high your heel shall come out. For example V4's normal foot position zeroed is an angle of around 19° to the floor.  If you need more or less you have to vary the dummy plane and than construct the heel in more or less right angle to that plane ... depending of your taste who the heel shall look. That dummy plane should lay a bit lower than the mesh break line foot/toe depending on how big you will design the sole. Platform = big distance, mocassin type flat sole = nearly no distance.

And have enough polygons around that foot/toe breakline. This part is bending !

Have fun with that modelling. It sounds more difficult than it is in the end.

Edited: One I forgot. If you have a difficult pose in mind like super high heel. The workflow is like above. But you will make a additional model exported from poser with the exact foot pose (export toe, foot, shin). Import this model additional into your modeller and without changing your shoe model use the new leg model to control your work. For this purpose angle the leg model with a fix point at the foot's back end. The foot heel is not bending much, so you can use this than a angle point. Don't worry that using this model the shin isn't any more parallel to the figures shin. This is normal. That additinal model is only used to control the foot and toe design.