Don't know how the 155 dash is, but attached is how I have it in the 145.
I chose not to have it turning on from the remote HU remote wire - as I find it interferes with the radio slightly. There's a power button on the remote which does the job perfectly!
For mounting - I've got it mounted on the floor - look at the holes on the player itself - if you hang it from the parcel shelf, it is harder for the heat to escape, as the holes are at the top, and the docking bay covers the bottom! It does get quite hot... but that may have something to do with the disk - I'm running a 7k rpm Maxtor. I just ordered the 10gb unit, then had a spare 40gb disk I slapped in it. Last week I filled that to the last few bytes so will get something bigger this week/next.
I advise you to upgrade to the open source firmware - much much better than the standard one, loads of options to play with
And customisable play screens, 'tis a cool player which works v well, should have been popular yrs ago.
As said, upgrade to the open source firmware on www.ssiamerica.com
's site, gives you whole load of options.
I'm well happy with it (apart from the first one, DOA on arrival, but 6thPlanet sorted it out next day with new unit), will be purchasing a 2nd car kit for other car, and might go for the home player/hi fi docking bay too.
If you can don't use the radio transmitter - it's quite good, but doesn't beat cable input!