Best way to integrate custom script with .NET's validator script

[P McGinness]

Basically, I've a JS function called ValidateForm(), which
returns true or false and controls if the form submits.

When I integrate this with .NET validators, the .NET
always adds it's own call to a function to the end of the
form onSubmit script. So if my function returns
false, .NETs function is still called and when it returns
true will basically render my code pointless.

I'm not entirely sure of the best way to integrate custom
code with .NET validation code; if I should write all the
script myself or if I should write an individual custom
function for each field on the page then attach them to
CustomValidators.

Any advise would be appreciated.

Cheers.