The 6809 uses the same Motorola bus arrangement as other Motorola 8bit processors. It's also not multiplexed on the 6809 so the support logic is quite simple.
A 74HC00 (U3) converts the 6809 E and RW lines into the Z80 \RD and \WR lines as expected by the RC2014 bus. The 74HC688 (U4) matches $FExx addresses as I/O space and generated \IORQ and \MREQ accordingly.
The various 6809 signals that don't fit on the standard bus are exposed via an additional 6 pin connector so that FIR, NMI and the like are usable. As with all my 68xx/65xx cards the E clock and RW lines can be jumpered to user pins 38/39 for use with Motorola style peripherals like the 6522 VIA card.
Have you used it in conjunction with the other standard RC2014 boards like the real time clock or compact flash storage? I've held off on buying an RC2014 kit because my true 8-bit love is the 6809. If your card works as a replacement for the Z80 I'd buy the whole lot.