Usually the polyethylene oxides, maize starch, magnesium stearate, colloidal silicon dioxide and hypromellose will retain some time release effect when crushed. Unfortunately I couldn't find the exact time release excipients for Xanax Retard as even though I went through several Dutch pages, it just wasn't listed. Crushing is probably the best you can hope for unless you can do chemical extractions, which just isn't worth it for alprazolam in my opinion.
I wouldn't take several though because a little too much and your a 12 hour zombie with a monster hangover. Blackouts aren't fun either when you come around and have to try to piece together what the hell happened and why everyone is mad at you.
Stay Safe unown.