Get .blend->SMD export script (believe it's called halflife SMD exporter or something), add a bone to your model (smd needs at least one bone), export via this script, then use this:
http://dplogin.com/forums/index.php?action=dlattach;topic=15307.0;attach=5433 and you should have your model. To use it in a map, put it into pball/models folder, then in BSP create an entity: func_model "model" "models/yourmodel.skm".
I have to warn you that making your own models, although easy in blender, is pain in the ass when trying to convert and use in BSP. I actually don't think you will get it right after first few tries, but don't give up, try to make all faces triangles/quads, try selecting or not a bone when exporting etc. till you know how to do it properly. Wish you good luck.
