If you choose to initialize the weights by using some pretrained weights you can do one out of two things. Either get some trained recognizer, extract the needed weights from there and copy them into the new system, or use some available generic predefined weights and initialize you system with these. Either way the performance of the initial system will be pretty bad, but it should at least be a lot better than if initialized with random weights.
If your must train a recognizer on a language for which you don't have any weights, then you'll have to think about which of your acoustic models (or phonemes) should be initialized with which of the available weights. So when switching from English to German you will have to model a few phonemes of German that do not occur in English. In this case you would just choose some 'similar' phoneme of the English recognizer. Also there will be some English phonemes that do not occur in German. You can just ignore these.
The do-it-yourself pages to this topic show how you can use the pretrained generic weights to initialize a recognizer.