[Max]

Typically, sealant AND o rings are not used together. I think as you do that someone has been in there before.

You can get the two volume SG series Service Manuals via the top FAQ thread for your engine.

 

[Max]

Volume two:
Page: ENGINE COOLING 6B-23

"For H25 engine
1) Install new O-rings (3) to water pump (1).
2) Install water pump to cylinder block.
Tightening Torque
Water pump bolt (H25 engine) (a): 27 N.m (2.7 kg-m, 19.5 lb-ft)
3) Install timing chain cover. Refer to Section 6A2.
4) Install oil pan, front differential housing, P/S system, cooling
system, intake manifold with throttle body and other parts.
5) Refill cooling system with coolant, front differential with gear oil,
P/S system with specified fluid and engine with engine oil.
6) Check wheel alignment referring to Section 3A.
7) Verify that there is no fuel leakage, water leakage and oil leakage
at each connection.
8) Connect negative (–) cable at battery."

The manual has accompanying diagrams as well.