How to set a very large REG_DWORD (> 999999999) using GPO templates

Hi,

We want to create a custom GPO template (ADM or ADMX/ADML) to allow our customers to configure the WebDav download file size limit. This is 47MB by default but has a maximum of 4GB if you set it directly in the registry. 

I'd like to do this ADM:

POLICY !!Download_size_limit_exp          

KEYNAME "SYSTEM\CurrentControlSet\Services\WebClient\Parameters"
EXPLAIN !!Download_size_limit_help

         PART "Download file size (bytes):"    NUMERIC DEFAULT 48128000 MIN 1024000 MAX 4096000000 SPIN 1024000
           VALUENAME "FileSizeLimitInBytes" 
         END PART

     END POLICY

The problem is the registry key is in bytes so I want 10 digits in the MAX value. It looks like you can only go to 9 digits (999999999) in the MAX value which would be about 1GB and the real maximum that could be set by a reg frag is 4GB. Is there anyway to do this with an ADM or ADMX/ADML? 

Thanks,

Nigel