Newbie - invoke-command and passing variables

Doing my head in as this must be easy but i'm just not getting it right.
Using PS 2.

I have a pre-defined ps script that takes some arguments passed at commend line, if I run this directly in ps it will work fine as expected:

C:\Scripts\Install.ps1 -i C:\Scripts\Installer.exe

where -i denotes passing the location of the installer executable, and C:\Scripts\Installer.exe is the physical path and exe being passed.

If I try to use this via invoke-command to run on a remote computer it appears that the variables aren't passed (I get a normal screen of options from the .exe as if I've not passed anything with the executable.

invoke-command -computername TTFBAK002.ttf.local c:\scripts\Install.ps1 -i C:\Scripts\Installer.exe

The relevant settings for remote execution are functioning (i'd not be getting the screens of options from the executable if it weren't) and I've tired various combinations of -scriptblock -arg etc etc but i'm not getting it right.

So... how on earth do you run a script remotely and pass it a couple of parameters.

PS. I don't want to develop a 'script' file to do this, I really need something that's a single command line (if it's possible)