Its the same MRP application form u need to fill in and send to embassy for Travel Document. In addition, u need to submit a letter requesting the travel document and stating that u will apply for MRP in Nepal. I beleive u r aware that Travel Document is valid for one way travel to Nepal. Additional documents needed are copies of ur passport and citizenship certificate, $40 money order and paid return envelope.
http://www.nepalembassyusa.org/passport.php