There's clearly no simple magic solution. I've not used BE but a quick look at the documentation shows that it can store its data either as XML files in the app_data folder or in a database.
If your BE data is stored in a database, and you have the ability to connect to both your BE database and your mojoPortal database in some toolkit that can push data around (e.g. MS Access), or you have tools that can export and import to a neutral formats like CSV, then you should be able to study how a post looks in both databases and push your content across.
If your data is stored in XML files, well you may be able to import/migrate these into the mojoPortal database, perhaps using VS if you are a developer, or again via something like MS Access if the XML files have a simple structure. Or you could first migrate your BE content into a database (see http://www.nyveldt.com/blog/page/blogenginenet-provider-migration ).
Migrating data like this will not look after any embedded images that are physically stored within the BE web site. Those will need to be manually moved and the links updated, unless the originals are going to stay visible where they are.
If none of the above makes any sense, then the only method is to re-post each article into your mojoPortal blog, perhaps setting the post dates to match your original posts, and copying and pasting the content. With 180 posts, this wouldn't take too long. Depending on your editor configuration in mojoPortal, you may find that pasting content copied from your published BE pages results in embedded styles and formatting problems. You may be better copying from the BE editor, and in particular from its html source view (assuming it has one) to the html source view in mojoPortal. This prevents the editor from being "clever", so gives you a straight copy, but you may still need to do some html cleaning and css work.