There's no mechanical way to convert CR to level adjustment. The DM has to adjudicate it. Level adjustment is rarely lower than challenge rating. In general, abilities which remain valuable at high level are worth a lot more than abilities which will be obsolete later on.
Gelatinous creature is actually quite low-powered. Its abilities are weak, and it has several drawbacks, like half speed and reduced ability scores. Many of its benefits (d10 hit dice) don't apply to player characters with levels, and some dangers like sneak attack and polymorph are more rarely used against PCs. The acid slam attack is no more powerful than a sword. I can't go into specific detail without effectively reproducing the entire creature template, but in the hands of PCs this is overall a weak template.
Sentry ooze mainly gives spell resistance (very powerful, worth at least a level on its own) and big ability score bonuses.
Combined, you have a race with Str +0, Dex +2, Con +6, Int 3, Wis +6, Cha +6. These ability score bonuses are very high: compare it to Half-Celestial, which has +4 level adjustment. That template also has spell resistance, a +4 bonus to specific saves. However, Half-Celestial also gains elemental resistances and damage reduction, flight, and some useful spell-like abilities.
Using Half-Celestial as a rough benchmark, we can very approximately place your combined ooze's level adjustment no higher than +4, and no lower than +3 (it's considerably better than drow, which is +2 and has spell resistance and minor ability score bonuses). As the DM, you have the final say here.
Personally, I'd suggest inventing your own ooze template or race closer to +1 or +2, to avoid lumbering your player with a high level penalty just because he wanted to play an ooze. You don't really need Spell Resistance and +6 Wisdom to represent an ooze; you really just need a Dexterity bonus, acidic touch, acid resistance, a racial bonus to Escape Artist checks, and a unique ability to squeeze through openings smaller than your head. That could easily be done within a +1 or +2 level adjustment.
There's also the Oozemaster prestige class in Masters of the Wild, although it's quite weak, as you have to be at least a 5th level spellcaster and you lose half your spellcasting progression.