Finally found out that you do need to roll your own. Using bits of code that I found on here and on the old email archive, I come up with this for transmitting one byte:

TXBYTE:
FOR COUNTER = 0 TO 7
DAT_SCU = TMPBYTE.7
@ NOP
@ NOP
@ NOP
@ NOP
@ NOP
@ NOP
@ NOP
@ NOP
CLK_SCU = 1 ' Make clock go high after 8 instructions.( = 32 x 125ns = 4us wait)
@ NOP
@ NOP
@ NOP
@ NOP
@ NOP
@ NOP
@ NOP
@ NOP
CLK_SCU = 0
TMPBYTE = TMPBYTE << 1
NEXT COUNTER
RETURN

And for receiving it:

RXBYTE:
FOR Counter = 0 TO 7
WHILE CLK = 0 : WEND 'Wait for clock to go high
TMPBYTE.0 = DAT 'Assign bit value on datapin to byte variable
IF Counter < 7 Then TMPBYTE = TMPBYTE << 1
WHILE CLK = 1 : WEND 'Wait for clock to go low before re-entering loop
NEXT
RETURN