Bulldog = bullcr*p. Get a bulldog cheapo system if you want a problem in 12 months. Both you list look like they’re ****; and both likely made by the same company that owns bulldog.
Were I to install one, which I might for the truck at some point, I’d get a clifford, viper, python, etc.. Which are all the same umbrella corporation now: http://www.directed.com/Brands/
http://Sonicelectronix.com will likely have a decent deal on one of the better ones mentioned. If you want it to actually work reasonably easy with some actual backing, then visit http://www.crutchfield.com/m_800/Car-Alarms-Remote-Start.html and talk to someone about what you want and what all you will need. They will provide the wiring diagrams with your purchase.
Visit this site on getting more information specific to installing aftermarket alarms and such. And here specifically is your requested info:
http://www.the12volt.com/installbay/vehiclewiring/1/yeard/Lexus.html (4th entry, 3rd post in that thread).
Realistically, if you have no experience with electrical work, take it to a shop. You really need some experience/knowledge doing this somewhere/from someone; likely as it’s an 2008, it will need a PATS bypass to function in addition to using relays for various things. These are not plug and play systems specific to your vehicle, they need adaptation. This is especially true of newer ones that have chipped keys for PATS, as they will require you to either sacrifice a key for the chip along with an additionally purchased module, or cloning an existing key’s chip for the additional module which doesn’t come with the base alarm/remote-start kit purchased.