The lcd-mod can be ordered from divineo. It has parallel and serial connections. I have one of the german LCDs connected to it via the parallel output. There is almost no documentation on the lcd-mod and xaddons simply does not respond.
In avalaunch and xbmc, you configure it as if it is a smartxx LCD. Perhaps, serial mode is emulated by the smartxx?
If you want to go cheap, get this and pick up one of the 20x2 parallel LCDs off of ebay for $9.99 shipped. I went with one of the german LCDs that are 20x4, but are tiny. The problem with these LCDs is that they are so tiny and the pin headers are smaller than standard. I ended up speding an extra $20 for the lcd-con which makes it easier to connect everything.
The LCD mod does not switch bioses or anything.
That alladin chip looks like another cheap route, if you want to add an LCD. I'd check wtih xbmc to see if it is supported.
I have no idea how the lcd-mod works. It may simply pass through L0-
L3 from the LPC which would be enough to operate in 4-bit mode for a parallel LCD. The other connections on a parallel LCD are Regsiter select (RS) set H?, Enable set H, R/W set L, Vss set L (ground), Vdd set H. contrast control can be obtained with a 10k pot connected to Vee, Vss, and Vdd.