Ok another hairbrained electronics question-
Would it be theoritically possible to take an infrared receiver off a certain circuit and in it's place put a TTL serial port (which only the receive line connected)?

The reason I'm asking is because I have this spare satellite receiver lying around and it might be cool to not have to use a IR blaster to use it with a homebrew PVR setup. It also might make channel changes faster..

Yes, if:

The signal voltage is compatible between the devices
The signal sense is correct, ie not inverted. UART outputs are normally inverted logic compared to RS232 levels, as the majority of level shifters are also inverters.
The IR unit actually produces some form of UART compatible serial signal in the first place. Consumer IR is often not a standard serial word, and also has a fairly high carrier frequency. Most modern IR RX sensors do all the work internally and give out a demodulated bitstream, but it may well not be as simple as 8,n,1.

pca