When I thought I was going to have to replace this on my SX-M due to potentially bad threads on the manifold block I found posts that say its possible. Here are the key elements I read about and those that have done it can provide additional info:
The block does come out towards the rear after removing the one nut that holds it in place
The trim pump hoses cannot be undone on the inside of the boat without significant disassembly e.g. engine removal so the key it to get a lot of slack on the trim pump hoses by either (1) taking them off at the pump end or (2) unmounting the trim pump
Once the block is out should have enough slack and clearance to get to the other side of the manifold block to remove the trim pump hoses.
Make sure to loosen the 4 trim cylinder hoses before pulling the manifold block
Use a new O-ring and nut when reinstalling
Lube the O-ring with O-ring compatible grease
Lube the o rings on the hoses with trim pump fluid
Trim hose nuts get torqued to only 84 to 108 inch pounds so not a lot and probably cannot get a torque wrench in there anyway, so tighten ‘just so’.