I've create this drink at the time I was working as a bartender in an Irish Pub in Rio de Janeiro. Took me two nights to figure out how to make a 1, 1/2 spirit drink that you wouldn't feel the taste of alcohol. :)

In a tall glass add the one shot of Gin (please, use Gilbey's Gin), next add half-shot of the Lemon Rum, next squeeze two limes and add the juice, next add the grenadine, then the fill with ice cubs and add the coke (warm) to the top of the glass.
Wait for 1:42 min. If you did it right, the coke should come down to the botton of the glass.

Drink with a straw aiming the dark area at bottom of the glass (coke) and it should taste like somekind of soda.

If you taste the gin, you'll have to mix it again. There's no "almost good" here, only two possibilities: Works and taste great or simply taste awful.

6 oz of Gilbey's Gin
3 oz of Bacardi Lemon
2 oz of grenadine
6 oz of lime juice

*If you want to try with another (and better) brand of gin, you'll have to change the recipe to disguise de alcohol. That could take some time, but I'll suggest change the coke and grenadine parts for start. If you have success, please tell me about it. :)