The only option I know of for the Blaujunk is an infrared (PAC?). For thses types, the transmitter portion needs to be placed to point at the head unit. THese are unreliable when the sun comes through the windshield.
The attached is a picture of my 852. I have installed the Soundgate Remote1 (cost me $129 sure the dealer cost is less than $100).
Email me and I will give more details.
Ross
99 PB SLT+
Alpine CDA-D852
With stock steering wheel controls