Chuck - thank you so much. Pentax Support was not helpful in my research so I appreciate your feedback. They told me the PC socket uses a standard PC cord, but the manual calls it a "5P sync socket." Admittedly, I do not know if those are a match. And when inquiring about operational voltage to avoid frying my flash, they simply told me, "There is no specification available for operational voltage. Pentax doesn't release specifications for matching non-Pentax accessories with the cameras."
I don't expect to use TTL in the wireless set up anyway because I'll keep my flash(es) in manual mode (whether with Pentax or a new camera system) so the lack of TTL options is not an issue.
Out of curiosity, have you insights on the following systems for the K20D cam and 540 flash? If I can get reliable results with any of these, I'd rather not drop that amount of money on the Elinchrom
Lastolite RF flash trigger system #2450 & 2451
Flash Triggers - Lastolite Limited
It's described as, “Battery operated wireless trigger system for battery operated flash guns and studio flash. Simply attach the transmitter to the hotshoe on your camera, and then attach your receiver unit to the flash gun which can be mounted onto a stand or other similar support brackets. The trigger.” The system has a range of 10 meters. The trigger operates at 433 MHZ. $77.83 and additional receiver units are $46.69 each. The only thing is I can’t find anyone that sells them in the states.
Hahnel Combi TF Remote Control & Flash Trigger for Canon, Pentax & Samsung DSLRs
http://www.bhphotovideo.com/bnh/controller/home?O=NavBar&A=getItemDetail&Q=&sku=723410&is=REG&si=rev#anchorToReadReviews
Price: $89.95
Flashpoint RC1, 3-in-1 Remote Control-Camera/Flash Trigger for Pentax
$59.95
Photoflex FlashFire, Battery Powered Wireless Trigger & Receiver Radio Slave Kit, 2.4GHz 16-Channel for StarFlash/ShoeMount Type Flashes
$89.99
Thank you again!