POKE CB45,00

This removes the code which subtracts one unit from the time.

CB44

SUB 01

POKE A620,00

This simply removes the following command, which would otherwise decrease the players lives.

A620

DEC (HL)

POKE BF59,C9

POKE A5D9,2A

This alters:

BF59

RET NZ

To simply return regardless of the flag:

BF59

RET

And also changes:

A5D9	JP NZ,A667

To the following (which is overwritten immediately, so just never actions the jump):

A5D9	LD HL,A667

POKE C272,nn

POKE C273,nn

For example, to set 2000 seconds:

POKE C272,00

POKE C273,20

Or, to set 750 seconds:

POKE C272,50

POKE C273,07