[Genome] how can I change the chain format to psl and then to axt ?

[Xiaolu.Huang at UCHSC.edu]

Dear bioinformaticians at ucsc genome,
 
Thanks for your previous prompt reply! I need to change the chain files to axt files. The only way I can find is the chaintopsl, but I do not know how to download it. also in the 
"usage: 
   chainToPsl in.chain tSizes qSizes target.lst query.lst out.psl 
  Where tSizes and qSizes are tab-delimited files with 
       <seqName><size> columns. "

I am afraid that I do not quite know what the tSizes and qSizes files should be.

Could you show me a way to convert a chain table file to axt files?

Thanks!

Xiaolu