Looks like you have all you need. Theory of how to test. Circuit diagrams. Source code.
The transistor test is, as expected, just 2x the diode test on each bipolar transistor junction. The diode test is just continuity testing in each direction. Continuity testing is applying a voltage and measuring the current by measuring the drop on a resistor (Ohm's Law).
Pretty straight forward as it's already doing each of these with pretty much the same circuit (transistor case). The rest is cosmetic software changes. I don't know PIC specifically but the C code for each seems pretty much like what you'd expect for a microcontroller.