If you are refering to the E series I6 then the only way is the unbolt the rocker train. The lash adjuster just sits in the end of the rocker.
My advice is to replace the whole set. Once one goes the rest will likely be on their way as well. They are around $25 each.
Make sure you:-
1. Use some clean rag to block the oil holes on the LHS of the head (so nothing falls down into the engine).
2. Remove and retighted the bolts in correct order.
3. Have a good torgue wrench that is able to be set at 25Nm,
4. Make sure you dip the bolts in light oil before screwing them back in.
5. I wrap a piece of masking or insulation tape around the adjuster and rocker arm to stop the adjusters falling out during removal and installation of the rocker train.
6. Remove the bits of rag before putting the rocket cover back one.
Not a difficult job but allow a couple of hours.
The XR family ---->
Muzza: a XR8 AU seriesIII...bog standard :)
TBH: (the better half) drives an ED XR6 wagon (Mock Dev 4 160rwkw, JMM extractors, 4 electric windows, Ghia door panels in XR trim, rear head & arm rests in XR trim, Momo s/wheel with Cruise, EL thermos, EBGT wheels, etc) things to come soon = EECV upgrade.