I just recarpeted our doghouse with some gray shag carpet to match the gray vinyl peel and stick tiles I put down last year. The old DH carpet had been glued down with yellow contact cement and wasn't too usable as a pattern, just a guide. So I laid all the old pieces (6 of them) face down on the new stuff and cut the new pieces a little oversize, knowing I'd probably have to trim it after placing.
>> The trick is to heat the bottom of the new carpet with a heat gun set on low or even a hair blow drier set on high. Heat before slobbering on the contact cement. The plastic and fiber backing that holds the carpet fibers softens VERY easily, then presses into the curves and around corners surprisingly well! just hold it in place a few seconds and TADA!!! Molded and ready to glue.
good luck