There's just no easy way of queing in a Partner.
The only way you'll get queing is to have a smart enough device to see a busy condition on the Partner set (supervised transfer), which is hard for two reasons.
First the device has to be smart enough: an advanced voicemail like an Amanda, Repartee, Key Voice, etc with Dialogic cards would do it. Each is pricey just to be used to que.
Second, supervised transfers require a true busy, no call waiting allowed. Partner extensions only show a true busy when all talk paths are busy or DND is invoked. If the set has DND invoked, it can't have voicemail coverage. For all talkpaths to be in use means a 3 way conference with both intercom paths in use.
Difficult to do on a Partner, it doesn't allow the luxury of COS options like tel-busy.
ASA is made to back up the receptionist at 10. Once the number of prescribed ASA rings happen, the ASA will pickup and place the caller on hold at 10, available for pickup by others, but held at 10. That can't be changed.
DXD will allow an unsupervised transfer only.