How to trap Command Line errors

Question

Sigh.  I have searched for 3 hours to the answer for my question.  I'm new to scripting, so perhaps this is the problem in my not finding a solution.
In a nutshell, I simply want to gracefully trap command line usage of a script.  I want to have my script accept a parameter (ie. a value) and a switch.
Example:  <script> -path <path> -set
The problem is that i cannot trap incorrect usage.  I would prefer <path> to be position one, and -switch to be position 2 of the parameters passed to the script.  I have not tried this "outside" of PS v2.0 ISE (ie. Powershell.exe). 
Of course, I would love it to work in both environments.
I KNOW that the ISE will prompt for missing mandatory parameters.  Great.  But incorrectly specified parameters causes Powershell ISE to "bomb-out".  That is, displaying error messages to an uninformed user whom views it as unintelligible.
Example of incorrect usage:  <script> -pat <path> -set
Again, I would LOVE to trap this, and display correct USAGE to the screen.  Unfortunately, this produces a Powershell error message which has proved unintelligible to "simple" users.
Perhaps I must accept that this is not possible in Powershell v2.0.  I simply want to program my script to CATCH this error and take the desired action.
HELP!!!  To the knowledgeable and generous Scripting Professionals.
If the directions say go straight, but I turn left, then right: Will I still get there?

Answer 1

Okay, I stripped down the script:
<#
===============================================================================
PQSC PowerShell Source File
NAME   :
AUTHOR : PQSC.Programmer
DATE   :
COMMENT: Expects -->U:\Users\Public\Public Programs\PQSC\Scripts<-- appended to Execution Path
         CommandLine to Test=powershell -debug -command "U:\Users\PQSC.Programmer\Documents\WindowsPowerShell\Get-FilesWithArchiveBitSet.ps1" -x
===============================================================================
#>
<# ---------------------------------------------
# Param1 is mandatory, Param2 is optional.
# Param1 should be:  -path <path>
# Param2 should be:  -Set
#>
[CmdletBinding()]
Param(
    [parameter(Mandatory=$true,Position=1)]
    [AllowNull()]
    [AllowEmptyString()]
    [String]
    $Path,
    [switch]
    $Set_Archive
PRODUCES THIS ERROR in PowerShell v2.0 ISE when invoke with:
powershell -debug -command "U:\Users\PQSC.Programmer\Documents\WindowsPowerShell\Get-FilesWithArchiveBitSet.ps1" -x
powershell.exe : Missing expression after unary operator '-'.
At line:1 char:11
+ powershell <<<<  -debug -command "U:\Users\PQSC.Programmer\Documents\WindowsPowerShell\Get-untitled2.ps1" -x
    + CategoryInfo          : NotSpecified: (Missing express...y operator '-'.:String) [], RemoteException
    + FullyQualifiedErrorId : NativeCommandError
At line:1 char:2
+ - <<<< debug -command U:\Users\PQSC.Programmer\Documents\WindowsPowerShell\Ge
t-untitled2.ps1 -x
    + CategoryInfo          : ParserError: (-:String) [], ParentContainsErrorR
   ecordException
    + FullyQualifiedErrorId : MissingExpressionAfterOperator
If the directions say go straight, but I turn left, then right: Will I still get there?