Depending on website software you use (wordpress, joomla, custom, etc), you might have a plugin or addon for each that supports multiple domains and search-engine pinging/seo. If that's the case, it should be possible.
I'm assuming your website layout is the same but you have a ".com" and ".de" TLD pointing to the same directory/software installation and a (auto?) language selector to choose between English and German.
Edit: (for quick readers)
It shouldn't need separate webspace for each site. What I do for my sites to get them submitted is use Sitemaps. I've never generated one myself, so I can't help in that aspect. However, you could generate sitemaps for each language (e.g. sitemap.en.xml.gz | sitemap.de.xml.gz) and have your application ping search engines with these sitemaps. Essentially, you'll have the same content but in different languages and it'll be in a sitemap which can be submitted to google/bing/yahoo/etc.
I used this method on a wordpress blog I had and every time I submitted/changed content, it would re-generate sitemaps (updating links/etc) and ping the search engines again.