This does work as well

-dll addons/metamod/dlls/metamod.dll -num_edicts 2047
There doesn't seem to be a cap limit either I had over 10,000 entities.
By default it looks like HL engine registers 900 edicts.
When I tried this on CS it adds an additional MAXPLAYERS * 15 on top of your num_edicts value.
[edit]
Just tried setting it to 1.
It seems to reset to the safety limit so in CS's case is MAXPLAYERS * 15 + 900
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