I do not have the K-x but the K-7. From my own (and limited) experience with MF, I suggest a few tricks:
- set the camera to centre focus; in absence of focus points, you know that always where the picture centre is;
- use the focus confirmation to have some idea of the typical MF setting; eventually adjust the MF ring slightly if you feel it is needed;
- in doubt, I take 2-3 identical shots, but from very slightly different positions; I often take the 2nd shot slightly forward (~5-10 cm) from my initial position and another slightly behind (~ 5-10 cm) from the initial shot; for example, by leaning slightly forward then slightly backward.
Hope that the comment will help...