Track Length TAG

I am writing a VB.NET application where I am using a ID3V2 library that doesn't return header information. All information is accessed by TAGs. I could modify the source code to return the header information, but decided to use the library DLL as is. Note that I am not modifying the length but just want the TAG, TLEN, to be in the file. If you have a better way, please advise.

Jerry B