Actually, just realized that this does not work for "None" either, only for "Check"

It is customary to post the script so that we can assist with an answer.  How can we know what is wrong if we don't know what the script is doing.

Thanks for the reply Louie, I was curious as to whether or not this was possible but I will post what I currently have. After checking the database, "None" is not a valid payment type, I had to set this to a blank string. I still am having difficulties setting the payment type to "Credit Card" however. This attempt i tried setting the payment type to what I know is the customer I am using's only credit card type on file. I have also tried setting the value to "Credit Card."

terms = ""
pay = ""
retVal = oBusObj.GetValue("TermsCode$", terms)

'Check
if terms = "00" or terms ="07" then
resul = oBusObj.SetValue("PaymentType$", "Check")
end if

'NONE
if terms = "35" then
resul = oBusObj.SetValue("PaymentType$", "")
end if

'Credit Card attempt 3
if terms = "5" then
resul = oBusObj.SetValue("PaymentType$", "AMEX")
end if

Actually this worked, I guess I will just need to grab the customers payment type as part of the script and then set accordingly unless you have another suggestion. 

How would I get a handle on the AR_Customer object to check the default payment type? This wouldn't be considered a child handle would it? 

You should be using the Case method.

Select [ Case ] testexpression 
    [ Case expressionlist 
        [ statements ] ] 
    [ Case Else 
        [ elsestatements ] ] 
End Select 

Set oCust = oBusObj.AsObject(oBusObj.GetChildHandle("CustomerNo"))