Use a prompt in a transformation file

I have set up a package to import transaction data from a flat file (CPMB/IMPORT). It works perfectly if I designate the destination member in the version dimension in the transformation file:

Version=FORECAST004

However, I would prefer that the user supplies this during the import so I don't need to keep maintaining the transformation file. I have used the SELECT Prompt() Command in the Prompt SECTION of the dynamic script editor to assign the user's selected version to the variable %DESTVER%. Now I would like to use that variable in the transformation file:

Version=*NEWCOL(%DESTVER%)

But the transformation file doesn't recognise the variable. It tries to write to a member called "%DESTVER%".

Is there a way I can achieve this?