Looks like it's a little more complicated on these beasts than on most BMWs;
BMW Workshop Manuals > X Series E53 X5 4.8is (N62-S) OFFRD > 2 Repair Instructions > 22 Engine And Gearbox Suspension > 32 Transmission Suspension, Autom. Transmis > 1 RA Replacing Rubber Mount For Transmission Mounting

RealOEM.com * BMW E53 X5 3.0i Gearbox suspension


Looks like you support the trans, pull the crossmember, then deal with the mount. No telling if the tools specified in the workshop manual is necessary or not...

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2001 X5 Sport 3.0/5-speed
1998 318ti/5-speed
1988 735i/5-speed
1984 528e/5-speed (soon to be M20B25-powered 525i!)