I have received an email from a Pentaxian, Mr Tomasz Kos, who is also an electronic engineer as well as a software programmer, that he has successfully developed a tethering software that can work with the K-x (and partially with the K-7 and maybe also for some other newer Pentax DSLRs). I have exchanged a few more emails with him and with his permission to me, I quote some of contents in his emails, as follows:-
"I want to control my camera from PC, but as I know doesn't exist any
software for this I start develop my program. I based on Pentax Remote Assistant and PKRemote. And now I shared beta version on my site. It allow control k-x from PC - change settings, save photo directly on HDD, shoot periodically. Additional I ported PKRemote to Windows and added support for k-x."
"My site is: https://sites.google.com/a/pentax.org.pl/tomaszkos/
But so far it is in Polish language, in future I will prepare English version.
So direct links to programs:
PK_Tether: https://sites.google.com/a/pentax.org.pl/tomaszkos/home/pktether/PK_Tether_0_1.zip?attredirects=0
PKRemote: https://sites.google.com/a/pentax.org.pl/tomaszkos/home/pkremote-for-windows/PKRemote_Executable_0_1.zip?attredirects=0
I informed about this program on Polish Pentax forum pentax.org.pl -
tread http://pentax.org.pl/viewtopic.php?t=33702"
"PKRemote as original is on GNU licence so it is free, and also source
code is available on my site. PK_Tether is freeware and will be. Maybe in future I will add button for donation on my site, but now when software is with bugs, and not
all functional is working I will even don't do this."
Hence, this software is free, but it is still under the beta testing stage. So, if you just want tethering with your K-x (which I don't need so far anyway), try the software and give your feedback(s) to the author so that improvements to the software could be made.
"Today I got information that PK_Tether is detected and shutter can be
released , but data from camera aren't displayed.
So it looks like, the communication with K7 it is similar to k-x but
status data is something different.
I think in near future K7 will be work like k-x."
So, the current version only work partially with the K-7, and possibly may not or may not work with the latest K-5 or K-r, as even the author has no idea himself up till now. But if you are just a K-x user, it should work (putting aside any bug that may exist). Anyway, if you have a K-5 or K-r, you can see if it works or how many things it will or will not do for you. If you've really tried, please drop a comment in reply to this post so that we shall know more.
Last but not least, if you don't read Polish (me neither, but it cannot be machine-translated by Google owing to some technical issues), here is a concise English version of all of Tom's Polish pages in one page, that he has just compiled:-
https://sites.google.com/a/pentax.org.pl/tomaszkos/en
Under which you can download the zipped version of the "PK_Tether".
As a final disclaimer, I just wish to tell that I have not tried the software myself (as I do not need it so far, as mentioned above). If you try, you're the one who agrees to install and use the software and should bear all the responsibilities at your own for what you do, as it always to be (true) for anything.
Related:-
Pentax K-5 Firmware 1.01 (w/ Hacks! And Upcoming New 645D Software for Tethering Support)
Tethering the Current Pentax DSLRs?